linux-kernel - Re: [PATCH 1/5] Free up pf flag PF

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Date:	Wed, 22 Dec 2010 10:17:26 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Venkatesh Pallipadi <venki@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	linux-kernel@...r.kernel.org, Paul Turner <pjt@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Shaun Ruffell <sruffell@...ium.com>
Subject: Re: [PATCH 1/5] Free up pf flag PF_KSOFTIRQD -v2

On Tue, 2010-12-21 at 17:09 -0800, Venkatesh Pallipadi wrote:
> Patchset:
> This is Part 2 of
> "Proper kernel irq time accounting -v4"
> http://lkml.indiana.edu/hypermail//linux/kernel/1010.0/01175.html
> 
> and applies 2.6.37-rc7.
> 
> Part 1 solves the way irqs are accounted in scheduler and tasks. This
> patchset solves how irq times are reported in /proc/stat and also not
> to include irq time in task->stime, etc.
> 
> Example:
> Running a cpu intensive loop and network intensive nc on a 4 CPU system
> and looking at 'top' output.
> 
> With vanilla kernel:
> Cpu0  :  0.0% us,  0.3% sy,  0.0% ni, 99.3% id,  0.0% wa,  0.0% hi,  0.3% si
> Cpu1  : 100.0% us,  0.0% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.0% hi,  0.0% si
> Cpu2  :  1.3% us, 27.2% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.0% hi, 71.4% si
> Cpu3  :  1.6% us,  1.3% sy,  0.0% ni, 96.7% id,  0.0% wa,  0.0% hi,  0.3% si
> 
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>  7555 root      20   0  1760  528  436 R  100  0.0   0:15.79 nc
>  7563 root      20   0  3632  268  204 R  100  0.0   0:13.13 loop
> 
> Notes:
> * Both tasks show 100% CPU, even when one of them is stuck on a CPU thats
>   processing 70% softirq.
> * no hardirq time.
> 
> 
> With "Part 1" patches:
> Cpu0  :  0.0% us,  0.0% sy,  0.0% ni, 100.0% id,  0.0% wa,  0.0% hi,  0.0% si
> Cpu1  : 100.0% us,  0.0% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.0% hi,  0.0% si
> Cpu2  :  2.0% us, 30.6% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.0% hi, 67.4% si
> Cpu3  :  0.7% us,  0.7% sy,  0.3% ni, 98.3% id,  0.0% wa,  0.0% hi,  0.0% si
> 
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>  6289 root      20   0  3632  268  204 R  100  0.0   2:18.67 loop
>  5737 root      20   0  1760  528  436 R   33  0.0   0:26.72 nc
> 
> Notes:
> * Tasks show 100% CPU and 33% CPU that correspond to their non-irq exec time.
> * no hardirq time.
> 
> 
> With "Part 1 + Part 2" patches:
> Cpu0  :  1.3% us,  1.0% sy,  0.3% ni, 97.0% id,  0.0% wa,  0.0% hi,  0.3% si
> Cpu1  : 99.3% us,  0.0% sy,  0.0% ni,  0.0% id,  0.0% wa,  0.7% hi,  0.0% si
> Cpu2  :  1.3% us, 31.5% sy,  0.0% ni,  0.0% id,  0.0% wa,  8.3% hi, 58.9% si
> Cpu3  :  1.0% us,  2.0% sy,  0.3% ni, 95.0% id,  0.0% wa,  0.7% hi,  1.0% si
> 
>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 20929 root      20   0  3632  268  204 R   99  0.0   3:48.25 loop
> 20796 root      20   0  1760  528  436 R   33  0.0   2:38.65 nc
> 
> Notes:
> * Both task exec time and hard irq time reported correctly.
> * hi and si time are based on fine granularity info and not on samples.
> * getrusage would give proper utime/stime split not including irq times
>   in that ratio.
> * Other places that report user/sys time like, cgroup cpuacct.stat will
>   now include only non-irq exectime.
> 
> This patch:

Your 0/x seem repeated in here for some reason... I would expect on the
below little bit.

> Cleanup patch, freeing up PF_KSOFTIRQD and use per_cpu ksoftirqd pointer
> instead, as suggested by Eric Dumazet.
> 
> Tested-by: Shaun Ruffell <sruffell@...ium.com>
> Signed-off-by: Venkatesh Pallipadi <venki@...gle.com>
> --- 
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