diff options
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/hugetlbpage.txt | 25 | ||||
| -rw-r--r-- | Documentation/vm/numa_memory_policy.txt | 4 | ||||
| -rw-r--r-- | Documentation/vm/pagemap.txt | 77 | ||||
| -rw-r--r-- | Documentation/vm/slabinfo.c | 4 | ||||
| -rw-r--r-- | Documentation/vm/slub.txt | 2 |
5 files changed, 106 insertions, 6 deletions
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt index 3102b81bef88..ea8714fcc3ad 100644 --- a/Documentation/vm/hugetlbpage.txt +++ b/Documentation/vm/hugetlbpage.txt @@ -77,7 +77,7 @@ memory that is preset in system at this time. System administrators may want to put this command in one of the local rc init files. This will enable the kernel to request huge pages early in the boot process (when the possibility of getting physical contiguous pages is still very high). In either -case, adminstrators will want to verify the number of hugepages actually +case, administrators will want to verify the number of hugepages actually allocated by checking the sysctl or meminfo. /proc/sys/vm/nr_overcommit_hugepages indicates how large the pool of @@ -95,6 +95,29 @@ this condition holds, however, no more surplus huge pages will be allowed on the system until one of the two sysctls are increased sufficiently, or the surplus huge pages go out of use and are freed. +With support for multiple hugepage pools at run-time available, much of +the hugepage userspace interface has been duplicated in sysfs. The above +information applies to the default hugepage size (which will be +controlled by the proc interfaces for backwards compatibility). The root +hugepage control directory is + + /sys/kernel/mm/hugepages + +For each hugepage size supported by the running kernel, a subdirectory +will exist, of the form + + hugepages-${size}kB + +Inside each of these directories, the same set of files will exist: + + nr_hugepages + nr_overcommit_hugepages + free_hugepages + resv_hugepages + surplus_hugepages + +which function as described above for the default hugepage-sized case. + If the user applications are going to request hugepages using mmap system call, then it is required that system administrator mount a file system of type hugetlbfs: diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt index bad16d3f6a47..6aaaeb38730c 100644 --- a/Documentation/vm/numa_memory_policy.txt +++ b/Documentation/vm/numa_memory_policy.txt @@ -58,7 +58,7 @@ most general to most specific: the policy at the time they were allocated. VMA Policy: A "VMA" or "Virtual Memory Area" refers to a range of a task's - virtual adddress space. A task may define a specific policy for a range + virtual address space. A task may define a specific policy for a range of its virtual address space. See the MEMORY POLICIES APIS section, below, for an overview of the mbind() system call used to set a VMA policy. @@ -353,7 +353,7 @@ follows: Because of this extra reference counting, and because we must lookup shared policies in a tree structure under spinlock, shared policies are - more expensive to use in the page allocation path. This is expecially + more expensive to use in the page allocation path. This is especially true for shared policies on shared memory regions shared by tasks running on different NUMA nodes. This extra overhead can be avoided by always falling back to task or system default policy for shared memory regions, diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt new file mode 100644 index 000000000000..ce72c0fe6177 --- /dev/null +++ b/Documentation/vm/pagemap.txt @@ -0,0 +1,77 @@ +pagemap, from the userspace perspective +--------------------------------------- + +pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow +userspace programs to examine the page tables and related information by +reading files in /proc. + +There are three components to pagemap: + + * /proc/pid/pagemap. This file lets a userspace process find out which + physical frame each virtual page is mapped to. It contains one 64-bit + value for each virtual page, containing the following data (from + fs/proc/task_mmu.c, above pagemap_read): + + * Bits 0-55 page frame number (PFN) if present + * Bits 0-4 swap type if swapped + * Bits 5-55 swap offset if swapped + * Bits 55-60 page shift (page size = 1<<page shift) + * Bit 61 reserved for future use + * Bit 62 page swapped + * Bit 63 page present + + If the page is not present but in swap, then the PFN contains an + encoding of the swap file number and the page's offset into the + swap. Unmapped pages return a null PFN. This allows determining + precisely which pages are mapped (or in swap) and comparing mapped + pages between processes. + + Efficient users of this interface will use /proc/pid/maps to + determine which areas of memory are actually mapped and llseek to + skip over unmapped regions. + + * /proc/kpagecount. This file contains a 64-bit count of the number of + times each page is mapped, indexed by PFN. + + * /proc/kpageflags. This file contains a 64-bit set of flags for each + page, indexed by PFN. + + The flags are (from fs/proc/proc_misc, above kpageflags_read): + + 0. LOCKED + 1. ERROR + 2. REFERENCED + 3. UPTODATE + 4. DIRTY + 5. LRU + 6. ACTIVE + 7. SLAB + 8. WRITEBACK + 9. RECLAIM + 10. BUDDY + +Using pagemap to do something useful: + +The general procedure for using pagemap to find out about a process' memory +usage goes like this: + + 1. Read /proc/pid/maps to determine which parts of the memory space are + mapped to what. + 2. Select the maps you are interested in -- all of them, or a particular + library, or the stack or the heap, etc. + 3. Open /proc/pid/pagemap and seek to the pages you would like to examine. + 4. Read a u64 for each page from pagemap. + 5. Open /proc/kpagecount and/or /proc/kpageflags. For each PFN you just + read, seek to that entry in the file, and read the data you want. + +For example, to find the "unique set size" (USS), which is the amount of +memory that a process is using that is not shared with any other process, +you can go through every map in the process, find the PFNs, look those up +in kpagecount, and tally up the number of pages that are only referenced +once. + +Other notes: + +Reading from any of the files will return -EINVAL if you are not starting +the read on an 8-byte boundary (e.g., if you seeked an odd number of bytes +into the file), or if the size of the read is not a multiple of 8 bytes. diff --git a/Documentation/vm/slabinfo.c b/Documentation/vm/slabinfo.c index e4230ed16ee7..df3227605d59 100644 --- a/Documentation/vm/slabinfo.c +++ b/Documentation/vm/slabinfo.c @@ -1,7 +1,7 @@ /* * Slabinfo: Tool to get reports about slabs * - * (C) 2007 sgi, Christoph Lameter <clameter@sgi.com> + * (C) 2007 sgi, Christoph Lameter * * Compile by: * @@ -99,7 +99,7 @@ void fatal(const char *x, ...) void usage(void) { - printf("slabinfo 5/7/2007. (c) 2007 sgi. clameter@sgi.com\n\n" + printf("slabinfo 5/7/2007. (c) 2007 sgi.\n\n" "slabinfo [-ahnpvtsz] [-d debugopts] [slab-regexp]\n" "-a|--aliases Show aliases\n" "-A|--activity Most active slabs first\n" diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt index 7c13f22a0c9e..bb1f5c6e28b3 100644 --- a/Documentation/vm/slub.txt +++ b/Documentation/vm/slub.txt @@ -266,4 +266,4 @@ of other objects. slub_debug=FZ,dentry -Christoph Lameter, <clameter@sgi.com>, May 30, 2007 +Christoph Lameter, May 30, 2007 |