linux-kernel - Re: [PATCH v3 0/4] Reduce NUMA related overhead in perf record profiling on large server systems

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Date:   Wed, 9 Jan 2019 15:41:25 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexey Budankov <alexey.budankov@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/4] Reduce NUMA related overhead in perf record
 profiling on large server systems

On Wed, Jan 09, 2019 at 12:19:20PM +0300, Alexey Budankov wrote:
> 
> It has been observed that trace reading thread runs on the same hw thread
> most of the time during perf record sampling collection. This scheduling
> layout leads up to 30% profiling overhead in case when some cpu intensive
> workload fully utilizes a large server system with NUMA. Overhead usually
> arises from remote (cross node) HW and memory references that have much
> longer latencies than local ones [1].
> 
> This patch set implements --affinity option that lowers 30% overhead
> completely for serial trace streaming (--affinity=cpu) and from 30% to
> 10% for AIO1 (--aio=1) trace streaming (--affinity=node|cpu).
> See OVERHEAD section below for more details.
> 
> Implemented extension provides users with capability to instruct Perf 
> tool to bounce trace reading thread's affinity mask between NUMA nodes 
> (--affinity=node) or assign the thread to the exact cpu (--affinity=cpu) 
> that trace buffer being processed belongs to.
> 
> The extension brings improvement in case of full system utilization when 
> Perf tool process contends with workload process on cpu cores. In case a 
> system has free cores to execute Perf tool process during profiling the 
> default system scheduling layout induces the lowest overhead.
> 
> The patch set has been validated on BT benchmark from NAS Parallel 
> Benchmarks [2] running on dual socket, 44 cores, 88 hw threads Broadwell 
> system with kernels v4.4-21-generic (Ubuntu 16.04) and v4.20.0-rc5 
> (tip perf/core). 
> 
> OVERHEAD:
> 			       BENCH REPORT BASED   ELAPSED TIME BASED
> 	  v4.20.0-rc5 
>           (tip perf/core):
> 				
> (current) SERIAL-SYS  / BASE : 1.27x (14.37/11.31), 1.29x (15.19/11.69)
> 	  SERIAL-NODE / BASE : 1.15x (13.04/11.31), 1.17x (13.79/11.69)
> 	  SERIAL-CPU  / BASE : 1.00x (11.32/11.31), 1.01x (11.89/11.69)
> 	
> 	  AIO1-SYS    / BASE : 1.29x (14.58/11.31), 1.29x (15.26/11.69)
> 	  AIO1-NODE   / BASE : 1.08x (12.23/11.31), 1,11x (13.01/11.69)
> 	  AIO1-CPU    / BASE : 1.07x (12.14/11.31), 1.08x (12.83/11.69)
> 
> 	  v4.4.0-21-generic
>           (Ubuntu 16.04 LTS):
> 
> (current) SERIAL-SYS  / BASE : 1.26x (13.73/10.87), 1.29x (14.69/11.32)
> 	  SERIAL-NODE / BASE : 1.19x (13.02/10.87), 1.23x (14.03/11.32)
> 	  SERIAL-CPU  / BASE : 1.03x (11.21/10.87), 1.07x (12.18/11.32)
> 	
> 	  AIO1-SYS    / BASE : 1.26x (13.73/10.87), 1.29x (14.69/11.32)
> 	  AIO1-NODE   / BASE : 1.10x (12.04/10.87), 1.15x (13.03/11.32)
> 	  AIO1-CPU    / BASE : 1.12x (12.20/10.87), 1.15x (13.09/11.32)
> 
> The patch set is generated for acme perf/core repository.
> 
> ---
> Alexey Budankov (4):
>   perf record: allocate affinity masks
>   perf record: bind the AIO user space buffers to nodes
>   perf record: apply affinity masks when reading mmap buffers
>   perf record: implement --affinity=node|cpu option


hi,
can't apply your code on latest Arnaldo's perf/core:

Applying: perf record: allocate affinity masks
Applying: perf record: bind the AIO user space buffers to nodes
Applying: perf record: apply affinity masks when reading mmap buffers
Applying: perf record: implement --affinity=node|cpu option
error: corrupt patch at line 62
Patch failed at 0004 perf record: implement --affinity=node|cpu option
Use 'git am --show-current-patch' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

jirka