diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/xen/Kconfig | 23 | ||||
| -rw-r--r-- | drivers/xen/Makefile | 2 | ||||
| -rw-r--r-- | drivers/xen/balloon.c | 16 | ||||
| -rw-r--r-- | drivers/xen/events/events_base.c | 12 | ||||
| -rw-r--r-- | drivers/xen/evtchn.c | 2 | ||||
| -rw-r--r-- | drivers/xen/tmem.c | 419 | ||||
| -rw-r--r-- | drivers/xen/xen-balloon.c | 2 | ||||
| -rw-r--r-- | drivers/xen/xen-selfballoon.c | 579 |
8 files changed, 24 insertions, 1031 deletions
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index ec6558b79e9d..79cc75096f42 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -10,21 +10,6 @@ config XEN_BALLOON the system to expand the domain's memory allocation, or alternatively return unneeded memory to the system. -config XEN_SELFBALLOONING - bool "Dynamically self-balloon kernel memory to target" - depends on XEN && XEN_BALLOON && CLEANCACHE && SWAP && XEN_TMEM - help - Self-ballooning dynamically balloons available kernel memory driven - by the current usage of anonymous memory ("committed AS") and - controlled by various sysfs-settable parameters. Configuring - FRONTSWAP is highly recommended; if it is not configured, self- - ballooning is disabled by default. If FRONTSWAP is configured, - frontswap-selfshrinking is enabled by default but can be disabled - with the 'tmem.selfshrink=0' kernel boot parameter; and self-ballooning - is enabled by default but can be disabled with the 'tmem.selfballooning=0' - kernel boot parameter. Note that systems without a sufficiently - large swap device should not enable self-ballooning. - config XEN_BALLOON_MEMORY_HOTPLUG bool "Memory hotplug support for Xen balloon driver" depends on XEN_BALLOON && MEMORY_HOTPLUG @@ -191,14 +176,6 @@ config SWIOTLB_XEN def_bool y select SWIOTLB -config XEN_TMEM - tristate - depends on !ARM && !ARM64 - default m if (CLEANCACHE || FRONTSWAP) - help - Shim to interface in-kernel Transcendent Memory hooks - (e.g. cleancache and frontswap) to Xen tmem hypercalls. - config XEN_PCIDEV_BACKEND tristate "Xen PCI-device backend driver" depends on PCI && X86 && XEN diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index ad3844d9f876..0c4efa6fe450 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -17,14 +17,12 @@ dom0-$(CONFIG_X86) += pcpu.o obj-$(CONFIG_XEN_DOM0) += $(dom0-y) obj-$(CONFIG_BLOCK) += biomerge.o obj-$(CONFIG_XEN_BALLOON) += xen-balloon.o -obj-$(CONFIG_XEN_SELFBALLOONING) += xen-selfballoon.o obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o obj-$(CONFIG_XEN_GRANT_DEV_ALLOC) += xen-gntalloc.o obj-$(CONFIG_XENFS) += xenfs/ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o obj-$(CONFIG_XEN_PVHVM) += platform-pci.o -obj-$(CONFIG_XEN_TMEM) += tmem.o obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/ diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 37a36c6b9f93..4e11de6cde81 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -535,8 +535,15 @@ static void balloon_process(struct work_struct *work) state = reserve_additional_memory(); } - if (credit < 0) - state = decrease_reservation(-credit, GFP_BALLOON); + if (credit < 0) { + long n_pages; + + n_pages = min(-credit, si_mem_available()); + state = decrease_reservation(n_pages, GFP_BALLOON); + if (state == BP_DONE && n_pages != -credit && + n_pages < totalreserve_pages) + state = BP_EAGAIN; + } state = update_schedule(state); @@ -575,6 +582,9 @@ static int add_ballooned_pages(int nr_pages) } } + if (si_mem_available() < nr_pages) + return -ENOMEM; + st = decrease_reservation(nr_pages, GFP_USER); if (st != BP_DONE) return -ENOMEM; @@ -707,7 +717,7 @@ static int __init balloon_init(void) balloon_stats.schedule_delay = 1; balloon_stats.max_schedule_delay = 32; balloon_stats.retry_count = 1; - balloon_stats.max_retry_count = RETRY_UNLIMITED; + balloon_stats.max_retry_count = 4; #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG set_online_page_callback(&xen_online_page); diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index ff9b51055b14..2e8570c09789 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -1294,7 +1294,7 @@ void rebind_evtchn_irq(int evtchn, int irq) } /* Rebind an evtchn so that it gets delivered to a specific cpu */ -int xen_rebind_evtchn_to_cpu(int evtchn, unsigned tcpu) +static int xen_rebind_evtchn_to_cpu(int evtchn, unsigned int tcpu) { struct evtchn_bind_vcpu bind_vcpu; int masked; @@ -1328,7 +1328,6 @@ int xen_rebind_evtchn_to_cpu(int evtchn, unsigned tcpu) return 0; } -EXPORT_SYMBOL_GPL(xen_rebind_evtchn_to_cpu); static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest, bool force) @@ -1342,6 +1341,15 @@ static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest, return ret; } +/* To be called with desc->lock held. */ +int xen_set_affinity_evtchn(struct irq_desc *desc, unsigned int tcpu) +{ + struct irq_data *d = irq_desc_get_irq_data(desc); + + return set_affinity_irq(d, cpumask_of(tcpu), false); +} +EXPORT_SYMBOL_GPL(xen_set_affinity_evtchn); + static void enable_dynirq(struct irq_data *data) { int evtchn = evtchn_from_irq(data->irq); diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c index f341b016672f..052b55a14ebc 100644 --- a/drivers/xen/evtchn.c +++ b/drivers/xen/evtchn.c @@ -447,7 +447,7 @@ static void evtchn_bind_interdom_next_vcpu(int evtchn) this_cpu_write(bind_last_selected_cpu, selected_cpu); /* unmask expects irqs to be disabled */ - xen_rebind_evtchn_to_cpu(evtchn, selected_cpu); + xen_set_affinity_evtchn(desc, selected_cpu); raw_spin_unlock_irqrestore(&desc->lock, flags); } diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c deleted file mode 100644 index 64d7479ad5ad..000000000000 --- a/drivers/xen/tmem.c +++ /dev/null @@ -1,419 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-only -/* - * Xen implementation for transcendent memory (tmem) - * - * Copyright (C) 2009-2011 Oracle Corp. All rights reserved. - * Author: Dan Magenheimer - */ - -#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt - -#include <linux/module.h> -#include <linux/kernel.h> -#include <linux/types.h> -#include <linux/init.h> -#include <linux/pagemap.h> -#include <linux/cleancache.h> -#include <linux/frontswap.h> - -#include <xen/xen.h> -#include <xen/interface/xen.h> -#include <xen/page.h> -#include <asm/xen/hypercall.h> -#include <asm/xen/hypervisor.h> -#include <xen/tmem.h> - -#ifndef CONFIG_XEN_TMEM_MODULE -bool __read_mostly tmem_enabled = false; - -static int __init enable_tmem(char *s) -{ - tmem_enabled = true; - return 1; -} -__setup("tmem", enable_tmem); -#endif - -#ifdef CONFIG_CLEANCACHE -static bool cleancache __read_mostly = true; -module_param(cleancache, bool, S_IRUGO); -static bool selfballooning __read_mostly = true; -module_param(selfballooning, bool, S_IRUGO); -#endif /* CONFIG_CLEANCACHE */ - -#ifdef CONFIG_FRONTSWAP -static bool frontswap __read_mostly = true; -module_param(frontswap, bool, S_IRUGO); -#else /* CONFIG_FRONTSWAP */ -#define frontswap (0) -#endif /* CONFIG_FRONTSWAP */ - -#ifdef CONFIG_XEN_SELFBALLOONING -static bool selfshrinking __read_mostly = true; -module_param(selfshrinking, bool, S_IRUGO); -#endif /* CONFIG_XEN_SELFBALLOONING */ - -#define TMEM_CONTROL 0 -#define TMEM_NEW_POOL 1 -#define TMEM_DESTROY_POOL 2 -#define TMEM_NEW_PAGE 3 -#define TMEM_PUT_PAGE 4 -#define TMEM_GET_PAGE 5 -#define TMEM_FLUSH_PAGE 6 -#define TMEM_FLUSH_OBJECT 7 -#define TMEM_READ 8 -#define TMEM_WRITE 9 -#define TMEM_XCHG 10 - -/* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */ -#define TMEM_POOL_PERSIST 1 -#define TMEM_POOL_SHARED 2 -#define TMEM_POOL_PAGESIZE_SHIFT 4 -#define TMEM_VERSION_SHIFT 24 - - -struct tmem_pool_uuid { - u64 uuid_lo; - u64 uuid_hi; -}; - -struct tmem_oid { - u64 oid[3]; -}; - -#define TMEM_POOL_PRIVATE_UUID { 0, 0 } - -/* flags for tmem_ops.new_pool */ -#define TMEM_POOL_PERSIST 1 -#define TMEM_POOL_SHARED 2 - -/* xen tmem foundation ops/hypercalls */ - -static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid, - u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len) -{ - struct tmem_op op; - int rc = 0; - - op.cmd = tmem_cmd; - op.pool_id = tmem_pool; - op.u.gen.oid[0] = oid.oid[0]; - op.u.gen.oid[1] = oid.oid[1]; - op.u.gen.oid[2] = oid.oid[2]; - op.u.gen.index = index; - op.u.gen.tmem_offset = tmem_offset; - op.u.gen.pfn_offset = pfn_offset; - op.u.gen.len = len; - set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn); - rc = HYPERVISOR_tmem_op(&op); - return rc; -} - -static int xen_tmem_new_pool(struct tmem_pool_uuid uuid, - u32 flags, unsigned long pagesize) -{ - struct tmem_op op; - int rc = 0, pageshift; - - for (pageshift = 0; pagesize != 1; pageshift++) - pagesize >>= 1; - flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT; - flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT; - op.cmd = TMEM_NEW_POOL; - op.u.new.uuid[0] = uuid.uuid_lo; - op.u.new.uuid[1] = uuid.uuid_hi; - op.u.new.flags = flags; - rc = HYPERVISOR_tmem_op(&op); - return rc; -} - -/* xen generic tmem ops */ - -static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid, - u32 index, struct page *page) -{ - return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index, - xen_page_to_gfn(page), 0, 0, 0); -} - -static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid, - u32 index, struct page *page) -{ - return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index, - xen_page_to_gfn(page), 0, 0, 0); -} - -static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index) -{ - return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index, - 0, 0, 0, 0); -} - -static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid) -{ - return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0); -} - - -#ifdef CONFIG_CLEANCACHE -static int xen_tmem_destroy_pool(u32 pool_id) -{ - struct tmem_oid oid = { { 0 } }; - - return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0); -} - -/* cleancache ops */ - -static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key, - pgoff_t index, struct page *page) -{ - u32 ind = (u32) index; - struct tmem_oid oid = *(struct tmem_oid *)&key; - - if (pool < 0) - return; - if (ind != index) - return; - mb(); /* ensure page is quiescent; tmem may address it with an alias */ - (void)xen_tmem_put_page((u32)pool, oid, ind, page); -} - -static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key, - pgoff_t index, struct page *page) -{ - u32 ind = (u32) index; - struct tmem_oid oid = *(struct tmem_oid *)&key; - int ret; - - /* translate return values to linux semantics */ - if (pool < 0) - return -1; - if (ind != index) - return -1; - ret = xen_tmem_get_page((u32)pool, oid, ind, page); - if (ret == 1) - return 0; - else - return -1; -} - -static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key, - pgoff_t index) -{ - u32 ind = (u32) index; - struct tmem_oid oid = *(struct tmem_oid *)&key; - - if (pool < 0) - return; - if (ind != index) - return; - (void)xen_tmem_flush_page((u32)pool, oid, ind); -} - -static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key) -{ - struct tmem_oid oid = *(struct tmem_oid *)&key; - - if (pool < 0) - return; - (void)xen_tmem_flush_object((u32)pool, oid); -} - -static void tmem_cleancache_flush_fs(int pool) -{ - if (pool < 0) - return; - (void)xen_tmem_destroy_pool((u32)pool); -} - -static int tmem_cleancache_init_fs(size_t pagesize) -{ - struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID; - - return xen_tmem_new_pool(uuid_private, 0, pagesize); -} - -static int tmem_cleancache_init_shared_fs(uuid_t *uuid, size_t pagesize) -{ - struct tmem_pool_uuid shared_uuid; - - shared_uuid.uuid_lo = *(u64 *)&uuid->b[0]; - shared_uuid.uuid_hi = *(u64 *)&uuid->b[8]; - return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize); -} - -static const struct cleancache_ops tmem_cleancache_ops = { - .put_page = tmem_cleancache_put_page, - .get_page = tmem_cleancache_get_page, - .invalidate_page = tmem_cleancache_flush_page, - .invalidate_inode = tmem_cleancache_flush_inode, - .invalidate_fs = tmem_cleancache_flush_fs, - .init_shared_fs = tmem_cleancache_init_shared_fs, - .init_fs = tmem_cleancache_init_fs -}; -#endif - -#ifdef CONFIG_FRONTSWAP -/* frontswap tmem operations */ - -/* a single tmem poolid is used for all frontswap "types" (swapfiles) */ -static int tmem_frontswap_poolid; - -/* - * Swizzling increases objects per swaptype, increasing tmem concurrency - * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS - */ -#define SWIZ_BITS 4 -#define SWIZ_MASK ((1 << SWIZ_BITS) - 1) -#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK)) -#define iswiz(_ind) (_ind >> SWIZ_BITS) - -static inline struct tmem_oid oswiz(unsigned type, u32 ind) -{ - struct tmem_oid oid = { .oid = { 0 } }; - oid.oid[0] = _oswiz(type, ind); - return oid; -} - -/* returns 0 if the page was successfully put into frontswap, -1 if not */ -static int tmem_frontswap_store(unsigned type, pgoff_t offset, - struct page *page) -{ - u64 ind64 = (u64)offset; - u32 ind = (u32)offset; - int pool = tmem_frontswap_poolid; - int ret; - - /* THP isn't supported */ - if (PageTransHuge(page)) - return -1; - - if (pool < 0) - return -1; - if (ind64 != ind) - return -1; - mb(); /* ensure page is quiescent; tmem may address it with an alias */ - ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), page); - /* translate Xen tmem return values to linux semantics */ - if (ret == 1) - return 0; - else - return -1; -} - -/* - * returns 0 if the page was successfully gotten from frontswap, -1 if - * was not present (should never happen!) - */ -static int tmem_frontswap_load(unsigned type, pgoff_t offset, - struct page *page) -{ - u64 ind64 = (u64)offset; - u32 ind = (u32)offset; - int pool = tmem_frontswap_poolid; - int ret; - - if (pool < 0) - return -1; - if (ind64 != ind) - return -1; - ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), page); - /* translate Xen tmem return values to linux semantics */ - if (ret == 1) - return 0; - else - return -1; -} - -/* flush a single page from frontswap */ -static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset) -{ - u64 ind64 = (u64)offset; - u32 ind = (u32)offset; - int pool = tmem_frontswap_poolid; - - if (pool < 0) - return; - if (ind64 != ind) - return; - (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind)); -} - -/* flush all pages from the passed swaptype */ -static void tmem_frontswap_flush_area(unsigned type) -{ - int pool = tmem_frontswap_poolid; - int ind; - - if (pool < 0) - return; - for (ind = SWIZ_MASK; ind >= 0; ind--) - (void)xen_tmem_flush_object(pool, oswiz(type, ind)); -} - -static void tmem_frontswap_init(unsigned ignored) -{ - struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID; - - /* a single tmem poolid is used for all frontswap "types" (swapfiles) */ - if (tmem_frontswap_poolid < 0) - tmem_frontswap_poolid = - xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE); -} - -static struct frontswap_ops tmem_frontswap_ops = { - .store = tmem_frontswap_store, - .load = tmem_frontswap_load, - .invalidate_page = tmem_frontswap_flush_page, - .invalidate_area = tmem_frontswap_flush_area, - .init = tmem_frontswap_init -}; -#endif - -static int __init xen_tmem_init(void) -{ - if (!xen_domain()) - return 0; -#ifdef CONFIG_FRONTSWAP - if (tmem_enabled && frontswap) { - char *s = ""; - - tmem_frontswap_poolid = -1; - frontswap_register_ops(&tmem_frontswap_ops); - pr_info("frontswap enabled, RAM provided by Xen Transcendent Memory%s\n", - s); - } -#endif -#ifdef CONFIG_CLEANCACHE - BUILD_BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid)); - if (tmem_enabled && cleancache) { - int err; - - err = cleancache_register_ops(&tmem_cleancache_ops); - if (err) - pr_warn("xen-tmem: failed to enable cleancache: %d\n", - err); - else - pr_info("cleancache enabled, RAM provided by " - "Xen Transcendent Memory\n"); - } -#endif -#ifdef CONFIG_XEN_SELFBALLOONING - /* - * There is no point of driving pages to the swap system if they - * aren't going anywhere in tmem universe. - */ - if (!frontswap) { - selfshrinking = false; - selfballooning = false; - } - xen_selfballoon_init(selfballooning, selfshrinking); -#endif - return 0; -} - -module_init(xen_tmem_init) -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>"); -MODULE_DESCRIPTION("Shim to Xen transcendent memory"); diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c index a67236b02452..6d12fc368210 100644 --- a/drivers/xen/xen-balloon.c +++ b/drivers/xen/xen-balloon.c @@ -129,8 +129,6 @@ void xen_balloon_init(void) { register_balloon(&balloon_dev); - register_xen_selfballooning(&balloon_dev); - register_xenstore_notifier(&xenstore_notifier); } EXPORT_SYMBOL_GPL(xen_balloon_init); diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c deleted file mode 100644 index 246f6122c9ee..000000000000 --- a/drivers/xen/xen-selfballoon.c +++ /dev/null @@ -1,579 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/****************************************************************************** - * Xen selfballoon driver (and optional frontswap self-shrinking driver) - * - * Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp. - * - * This code complements the cleancache and frontswap patchsets to optimize - * support for Xen Transcendent Memory ("tmem"). The policy it implements - * is rudimentary and will likely improve over time, but it does work well - * enough today. - * - * Two functionalities are implemented here which both use "control theory" - * (feedback) to optimize memory utilization. In a virtualized environment - * such as Xen, RAM is often a scarce resource and we would like to ensure - * that each of a possibly large number of virtual machines is using RAM - * efficiently, i.e. using as little as possible when under light load - * and obtaining as much as possible when memory demands are high. - * Since RAM needs vary highly dynamically and sometimes dramatically, - * "hysteresis" is used, that is, memory target is determined not just - * on current data but also on past data stored in the system. - * - * "Selfballooning" creates memory pressure by managing the Xen balloon - * driver to decrease and increase available kernel memory, driven - * largely by the target value of "Committed_AS" (see /proc/meminfo). - * Since Committed_AS does not account for clean mapped pages (i.e. pages - * in RAM that are identical to pages on disk), selfballooning has the - * affect of pushing less frequently used clean pagecache pages out of - * kernel RAM and, presumably using cleancache, into Xen tmem where - * Xen can more efficiently optimize RAM utilization for such pages. - * - * When kernel memory demand unexpectedly increases faster than Xen, via - * the selfballoon driver, is able to (or chooses to) provide usable RAM, - * the kernel may invoke swapping. In most cases, frontswap is able - * to absorb this swapping into Xen tmem. However, due to the fact - * that the kernel swap subsystem assumes swapping occurs to a disk, - * swapped pages may sit on the disk for a very long time; even if - * the kernel knows the page will never be used again. This is because - * the disk space costs very little and can be overwritten when - * necessary. When such stale pages are in frontswap, however, they - * are taking up valuable real estate. "Frontswap selfshrinking" works - * to resolve this: When frontswap activity is otherwise stable - * and the guest kernel is not under memory pressure, the "frontswap - * selfshrinking" accounts for this by providing pressure to remove some - * pages from frontswap and return them to kernel memory. - * - * For both "selfballooning" and "frontswap-selfshrinking", a worker - * thread is used and sysfs tunables are provided to adjust the frequency - * and rate of adjustments to achieve the goal, as well as to disable one - * or both functions independently. - * - * While some argue that this functionality can and should be implemented - * in userspace, it has been observed that bad things happen (e.g. OOMs). - * - * System configuration note: Selfballooning should not be enabled on - * systems without a sufficiently large swap device configured; for best - * results, it is recommended that total swap be increased by the size - * of the guest memory. Note, that selfballooning should be disabled by default - * if frontswap is not configured. Similarly selfballooning should be enabled - * by default if frontswap is configured and can be disabled with the - * "tmem.selfballooning=0" kernel boot option. Finally, when frontswap is - * configured, frontswap-selfshrinking can be disabled with the - * "tmem.selfshrink=0" kernel boot option. - * - * Selfballooning is disallowed in domain0 and force-disabled. - * - */ - -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt - -#include <linux/kernel.h> -#include <linux/memblock.h> -#include <linux/swap.h> -#include <linux/mm.h> -#include <linux/mman.h> -#include <linux/workqueue.h> -#include <linux/device.h> -#include <xen/balloon.h> -#include <xen/tmem.h> -#include <xen/xen.h> - -/* Enable/disable with sysfs. */ -static int xen_selfballooning_enabled __read_mostly; - -/* - * Controls rate at which memory target (this iteration) approaches - * ultimate goal when memory need is increasing (up-hysteresis) or - * decreasing (down-hysteresis). Higher values of hysteresis cause - * slower increases/decreases. The default values for the various - * parameters were deemed reasonable by experimentation, may be - * workload-dependent, and can all be adjusted via sysfs. - */ -static unsigned int selfballoon_downhysteresis __read_mostly = 8; -static unsigned int selfballoon_uphysteresis __read_mostly = 1; - -/* In HZ, controls frequency of worker invocation. */ -static unsigned int selfballoon_interval __read_mostly = 5; - -/* - * Minimum usable RAM in MB for selfballooning target for balloon. - * If non-zero, it is added to totalreserve_pages and self-ballooning - * will not balloon below the sum. If zero, a piecewise linear function - * is calculated as a minimum and added to totalreserve_pages. Note that - * setting this value indiscriminately may cause OOMs and crashes. - */ -static unsigned int selfballoon_min_usable_mb; - -/* - * Amount of RAM in MB to add to the target number of pages. - * Can be used to reserve some more room for caches and the like. - */ -static unsigned int selfballoon_reserved_mb; - -static void selfballoon_process(struct work_struct *work); -static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process); - -#ifdef CONFIG_FRONTSWAP -#include <linux/frontswap.h> - -/* Enable/disable with sysfs. */ -static bool frontswap_selfshrinking __read_mostly; - -/* - * The default values for the following parameters were deemed reasonable - * by experimentation, may be workload-dependent, and can all be - * adjusted via sysfs. - */ - -/* Control rate for frontswap shrinking. Higher hysteresis is slower. */ -static unsigned int frontswap_hysteresis __read_mostly = 20; - -/* - * Number of selfballoon worker invocations to wait before observing that - * frontswap selfshrinking should commence. Note that selfshrinking does - * not use a separate worker thread. - */ -static unsigned int frontswap_inertia __read_mostly = 3; - -/* Countdown to next invocation of frontswap_shrink() */ -static unsigned long frontswap_inertia_counter; - -/* - * Invoked by the selfballoon worker thread, uses current number of pages - * in frontswap (frontswap_curr_pages()), previous status, and control - * values (hysteresis and inertia) to determine if frontswap should be - * shrunk and what the new frontswap size should be. Note that - * frontswap_shrink is essentially a partial swapoff that immediately - * transfers pages from the "swap device" (frontswap) back into kernel - * RAM; despite the name, frontswap "shrinking" is very different from - * the "shrinker" interface used by the kernel MM subsystem to reclaim - * memory. - */ -static void frontswap_selfshrink(void) -{ - static unsigned long cur_frontswap_pages; - unsigned long last_frontswap_pages; - unsigned long tgt_frontswap_pages; - - last_frontswap_pages = cur_frontswap_pages; - cur_frontswap_pages = frontswap_curr_pages(); - if (!cur_frontswap_pages || - (cur_frontswap_pages > last_frontswap_pages)) { - frontswap_inertia_counter = frontswap_inertia; - return; - } - if (frontswap_inertia_counter && --frontswap_inertia_counter) - return; - if (cur_frontswap_pages <= frontswap_hysteresis) - tgt_frontswap_pages = 0; - else - tgt_frontswap_pages = cur_frontswap_pages - - (cur_frontswap_pages / frontswap_hysteresis); - frontswap_shrink(tgt_frontswap_pages); - frontswap_inertia_counter = frontswap_inertia; -} - -#endif /* CONFIG_FRONTSWAP */ - -#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) -#define PAGES2MB(pages) ((pages) >> (20 - PAGE_SHIFT)) - -/* - * Use current balloon size, the goal (vm_committed_as), and hysteresis - * parameters to set a new target balloon size - */ -static void selfballoon_process(struct work_struct *work) -{ - unsigned long cur_pages, goal_pages, tgt_pages, floor_pages; - unsigned long useful_pages; - bool reset_timer = false; - - if (xen_selfballooning_enabled) { - cur_pages = totalram_pages(); - tgt_pages = cur_pages; /* default is no change */ - goal_pages = vm_memory_committed() + - totalreserve_pages + - MB2PAGES(selfballoon_reserved_mb); -#ifdef CONFIG_FRONTSWAP - /* allow space for frontswap pages to be repatriated */ - if (frontswap_selfshrinking) - goal_pages += frontswap_curr_pages(); -#endif - if (cur_pages > goal_pages) - tgt_pages = cur_pages - - ((cur_pages - goal_pages) / - selfballoon_downhysteresis); - else if (cur_pages < goal_pages) - tgt_pages = cur_pages + - ((goal_pages - cur_pages) / - selfballoon_uphysteresis); - /* else if cur_pages == goal_pages, no change */ - useful_pages = max_pfn - totalreserve_pages; - if (selfballoon_min_usable_mb != 0) - floor_pages = totalreserve_pages + - MB2PAGES(selfballoon_min_usable_mb); - /* piecewise linear function ending in ~3% slope */ - else if (useful_pages < MB2PAGES(16)) - floor_pages = max_pfn; /* not worth ballooning */ - else if (useful_pages < MB2PAGES(64)) - floor_pages = totalreserve_pages + MB2PAGES(16) + - ((useful_pages - MB2PAGES(16)) >> 1); - else if (useful_pages < MB2PAGES(512)) - floor_pages = totalreserve_pages + MB2PAGES(40) + - ((useful_pages - MB2PAGES(40)) >> 3); - else /* useful_pages >= MB2PAGES(512) */ - floor_pages = totalreserve_pages + MB2PAGES(99) + - ((useful_pages - MB2PAGES(99)) >> 5); - if (tgt_pages < floor_pages) - tgt_pages = floor_pages; - balloon_set_new_target(tgt_pages + - balloon_stats.current_pages - totalram_pages()); - reset_timer = true; - } -#ifdef CONFIG_FRONTSWAP - if (frontswap_selfshrinking) { - frontswap_selfshrink(); - reset_timer = true; - } -#endif - if (reset_timer) - schedule_delayed_work(&selfballoon_worker, - selfballoon_interval * HZ); -} - -#ifdef CONFIG_SYSFS - -#include <linux/capability.h> - -#define SELFBALLOON_SHOW(name, format, args...) \ - static ssize_t show_##name(struct device *dev, \ - struct device_attribute *attr, \ - char *buf) \ - { \ - return sprintf(buf, format, ##args); \ - } - -SELFBALLOON_SHOW(selfballooning, "%d\n", xen_selfballooning_enabled); - -static ssize_t store_selfballooning(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - bool was_enabled = xen_selfballooning_enabled; - unsigned long tmp; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - - err = kstrtoul(buf, 10, &tmp); - if (err) - return err; - if ((tmp != 0) && (tmp != 1)) - return -EINVAL; - - xen_selfballooning_enabled = !!tmp; - if (!was_enabled && xen_selfballooning_enabled) - schedule_delayed_work(&selfballoon_worker, - selfballoon_interval * HZ); - - return count; -} - -static DEVICE_ATTR(selfballooning, S_IRUGO | S_IWUSR, - show_selfballooning, store_selfballooning); - -SELFBALLOON_SHOW(selfballoon_interval, "%d\n", selfballoon_interval); - -static ssize_t store_selfballoon_interval(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - selfballoon_interval = val; - return count; -} - -static DEVICE_ATTR(selfballoon_interval, S_IRUGO | S_IWUSR, - show_selfballoon_interval, store_selfballoon_interval); - -SELFBALLOON_SHOW(selfballoon_downhys, "%d\n", selfballoon_downhysteresis); - -static ssize_t store_selfballoon_downhys(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - selfballoon_downhysteresis = val; - return count; -} - -static DEVICE_ATTR(selfballoon_downhysteresis, S_IRUGO | S_IWUSR, - show_selfballoon_downhys, store_selfballoon_downhys); - - -SELFBALLOON_SHOW(selfballoon_uphys, "%d\n", selfballoon_uphysteresis); - -static ssize_t store_selfballoon_uphys(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - selfballoon_uphysteresis = val; - return count; -} - -static DEVICE_ATTR(selfballoon_uphysteresis, S_IRUGO | S_IWUSR, - show_selfballoon_uphys, store_selfballoon_uphys); - -SELFBALLOON_SHOW(selfballoon_min_usable_mb, "%d\n", - selfballoon_min_usable_mb); - -static ssize_t store_selfballoon_min_usable_mb(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - selfballoon_min_usable_mb = val; - return count; -} - -static DEVICE_ATTR(selfballoon_min_usable_mb, S_IRUGO | S_IWUSR, - show_selfballoon_min_usable_mb, - store_selfballoon_min_usable_mb); - -SELFBALLOON_SHOW(selfballoon_reserved_mb, "%d\n", - selfballoon_reserved_mb); - -static ssize_t store_selfballoon_reserved_mb(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - selfballoon_reserved_mb = val; - return count; -} - -static DEVICE_ATTR(selfballoon_reserved_mb, S_IRUGO | S_IWUSR, - show_selfballoon_reserved_mb, - store_selfballoon_reserved_mb); - - -#ifdef CONFIG_FRONTSWAP -SELFBALLOON_SHOW(frontswap_selfshrinking, "%d\n", frontswap_selfshrinking); - -static ssize_t store_frontswap_selfshrinking(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - bool was_enabled = frontswap_selfshrinking; - unsigned long tmp; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &tmp); - if (err) - return err; - if ((tmp != 0) && (tmp != 1)) - return -EINVAL; - frontswap_selfshrinking = !!tmp; - if (!was_enabled && !xen_selfballooning_enabled && - frontswap_selfshrinking) - schedule_delayed_work(&selfballoon_worker, - selfballoon_interval * HZ); - - return count; -} - -static DEVICE_ATTR(frontswap_selfshrinking, S_IRUGO | S_IWUSR, - show_frontswap_selfshrinking, store_frontswap_selfshrinking); - -SELFBALLOON_SHOW(frontswap_inertia, "%d\n", frontswap_inertia); - -static ssize_t store_frontswap_inertia(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - frontswap_inertia = val; - frontswap_inertia_counter = val; - return count; -} - -static DEVICE_ATTR(frontswap_inertia, S_IRUGO | S_IWUSR, - show_frontswap_inertia, store_frontswap_inertia); - -SELFBALLOON_SHOW(frontswap_hysteresis, "%d\n", frontswap_hysteresis); - -static ssize_t store_frontswap_hysteresis(struct device *dev, - struct device_attribute *attr, - const char *buf, - size_t count) -{ - unsigned long val; - int err; - - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - err = kstrtoul(buf, 10, &val); - if (err) - return err; - if (val == 0) - return -EINVAL; - frontswap_hysteresis = val; - return count; -} - -static DEVICE_ATTR(frontswap_hysteresis, S_IRUGO | S_IWUSR, - show_frontswap_hysteresis, store_frontswap_hysteresis); - -#endif /* CONFIG_FRONTSWAP */ - -static struct attribute *selfballoon_attrs[] = { - &dev_attr_selfballooning.attr, - &dev_attr_selfballoon_interval.attr, - &dev_attr_selfballoon_downhysteresis.attr, - &dev_attr_selfballoon_uphysteresis.attr, - &dev_attr_selfballoon_min_usable_mb.attr, - &dev_attr_selfballoon_reserved_mb.attr, -#ifdef CONFIG_FRONTSWAP - &dev_attr_frontswap_selfshrinking.attr, - &dev_attr_frontswap_hysteresis.attr, - &dev_attr_frontswap_inertia.attr, -#endif - NULL -}; - -static const struct attribute_group selfballoon_group = { - .name = "selfballoon", - .attrs = selfballoon_attrs -}; -#endif - -int register_xen_selfballooning(struct device *dev) -{ - int error = -1; - -#ifdef CONFIG_SYSFS - error = sysfs_create_group(&dev->kobj, &selfballoon_group); -#endif - return error; -} -EXPORT_SYMBOL(register_xen_selfballooning); - -int xen_selfballoon_init(bool use_selfballooning, bool use_frontswap_selfshrink) -{ - bool enable = false; - unsigned long reserve_pages; - - if (!xen_domain()) - return -ENODEV; - - if (xen_initial_domain()) { - pr_info("Xen selfballooning driver disabled for domain0\n"); - return -ENODEV; - } - - xen_selfballooning_enabled = tmem_enabled && use_selfballooning; - if (xen_selfballooning_enabled) { - pr_info("Initializing Xen selfballooning driver\n"); - enable = true; - } -#ifdef CONFIG_FRONTSWAP - frontswap_selfshrinking = tmem_enabled && use_frontswap_selfshrink; - if (frontswap_selfshrinking) { - pr_info("Initializing frontswap selfshrinking driver\n"); - enable = true; - } -#endif - if (!enable) - return -ENODEV; - - /* - * Give selfballoon_reserved_mb a default value(10% of total ram pages) - * to make selfballoon not so aggressive. - * - * There are mainly two reasons: - * 1) The original goal_page didn't consider some pages used by kernel - * space, like slab pages and memory used by device drivers. - * - * 2) The balloon driver may not give back memory to guest OS fast - * enough when the workload suddenly aquries a lot of physical memory. - * - * In both cases, the guest OS will suffer from memory pressure and - * OOM killer may be triggered. - * By reserving extra 10% of total ram pages, we can keep the system - * much more reliably and response faster in some cases. - */ - if (!selfballoon_reserved_mb) { - reserve_pages = totalram_pages() / 10; - selfballoon_reserved_mb = PAGES2MB(reserve_pages); - } - schedule_delayed_work(&selfballoon_worker, selfballoon_interval * HZ); - - return 0; -} -EXPORT_SYMBOL(xen_selfballoon_init); 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