linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2017-03-02	sched/headers: Prepare for new header dependencies before moving code to <linux/sched/loadavg.h>	Ingo Molnar	1	-0/+1
	We are going to split <linux/sched/loadavg.h> out of <linux/sched.h>, which will have to be picked up from a couple of .c files. Create a trivial placeholder <linux/sched/topology.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-13	sched/core: Correct off by one bug in load migration calculation	Thomas Gleixner	1	-4/+4
	The move of calc_load_migrate() from CPU_DEAD to CPU_DYING did not take into account that the function is now called from a thread running on the outgoing CPU. As a result a cpu unplug leakes a load of 1 into the global load accounting mechanism. Fix it by adjusting for the currently running thread which calls calc_load_migrate(). Reported-by: Anton Blanchard <anton@samba.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: rt@linutronix.de Cc: shreyas@linux.vnet.ibm.com Fixes: e9cd8fa4fcfd: ("sched/migration: Move calc_load_migrate() into CPU_DYING") Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1607121744350.4083@nanos Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12	sched/loadavg: Fix loadavg artifacts on fully idle and on fully loaded systems	Vik Heyndrickx	1	-4/+7
	Systems show a minimal load average of 0.00, 0.01, 0.05 even when they have no load at all. Uptime and /proc/loadavg on all systems with kernels released during the last five years up until kernel version 4.6-rc5, show a 5- and 15-minute minimum loadavg of 0.01 and 0.05 respectively. This should be 0.00 on idle systems, but the way the kernel calculates this value prevents it from getting lower than the mentioned values. Likewise but not as obviously noticeable, a fully loaded system with no processes waiting, shows a maximum 1/5/15 loadavg of 1.00, 0.99, 0.95 (multiplied by number of cores). Once the (old) load becomes 93 or higher, it mathematically can never get lower than 93, even when the active (load) remains 0 forever. This results in the strange 0.00, 0.01, 0.05 uptime values on idle systems. Note: 93/2048 = 0.0454..., which rounds up to 0.05. It is not correct to add a 0.5 rounding (=1024/2048) here, since the result from this function is fed back into the next iteration again, so the result of that +0.5 rounding value then gets multiplied by (2048-2037), and then rounded again, so there is a virtual "ghost" load created, next to the old and active load terms. By changing the way the internally kept value is rounded, that internal value equivalent now can reach 0.00 on idle, and 1.00 on full load. Upon increasing load, the internally kept load value is rounded up, when the load is decreasing, the load value is rounded down. The modified code was tested on nohz=off and nohz kernels. It was tested on vanilla kernel 4.6-rc5 and on centos 7.1 kernel 3.10.0-327. It was tested on single, dual, and octal cores system. It was tested on virtual hosts and bare hardware. No unwanted effects have been observed, and the problems that the patch intended to fix were indeed gone. Tested-by: Damien Wyart <damien.wyart@free.fr> Signed-off-by: Vik Heyndrickx <vik.heyndrickx@veribox.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Doug Smythies <dsmythies@telus.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 0f004f5a696a ("sched: Cure more NO_HZ load average woes") Link: http://lkml.kernel.org/r/e8d32bff-d544-7748-72b5-3c86cc71f09f@veribox.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-05-08	sched: Move the loadavg code to a more obvious location	Peter Zijlstra	1	-0/+394
	I could not find the loadavg code.. turns out it was hidden in a file called proc.c. It further got mingled up with the cruft per rq load indexes (which we really want to get rid of). Move the per rq load indexes into the fair.c load-balance code (that's the only thing that uses them) and rename proc.c to loadavg.c so we can find it again. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Thomas Gleixner <tglx@linutronix.de> [ Did minor cleanups to the code. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>