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From: Andi Kleen <andi@firstfloor.org>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>, Jiri Olsa <jolsa@redhat.com>,
	Andi Kleen <andi@firstfloor.org>,
	acme@kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org,
	eranian@google.com, kan.liang@linux.intel.com,
	peterz@infradead.org
Subject: Re: [PATCH v2 4/9] perf affinity: Add infrastructure to save/restore affinity
Date: Wed, 23 Oct 2019 10:19:04 -0700	[thread overview]
Message-ID: <20191023171904.ft735ormkro6tahp@two.firstfloor.org> (raw)
In-Reply-To: <6ac1024c-bc73-87cd-31d2-819abee60137@linux.intel.com>

On Wed, Oct 23, 2019 at 07:16:13PM +0300, Alexey Budankov wrote:
> 
> On 23.10.2019 17:52, Andi Kleen wrote:
> > On Wed, Oct 23, 2019 at 04:30:49PM +0200, Jiri Olsa wrote:
> >> On Wed, Oct 23, 2019 at 06:02:35AM -0700, Andi Kleen wrote:
> >>> On Wed, Oct 23, 2019 at 11:59:11AM +0200, Jiri Olsa wrote:
> >>>> On Sun, Oct 20, 2019 at 10:51:57AM -0700, Andi Kleen wrote:
> >>>>
> >>>> SNIP
> >>>>
> >>>>> +}
> >>>>> diff --git a/tools/perf/util/affinity.h b/tools/perf/util/affinity.h
> >>>>> new file mode 100644
> >>>>> index 000000000000..e56148607e33
> >>>>> --- /dev/null
> >>>>> +++ b/tools/perf/util/affinity.h
> >>>>> @@ -0,0 +1,15 @@
> >>>>> +// SPDX-License-Identifier: GPL-2.0
> >>>>> +#ifndef AFFINITY_H
> >>>>> +#define AFFINITY_H 1
> >>>>> +
> >>>>> +struct affinity {
> >>>>> +	unsigned char *orig_cpus;
> >>>>> +	unsigned char *sched_cpus;
> >>>>
> >>>> why not use cpu_set_t directly?
> >>>
> >>> Because it's too small in glibc (only 1024 CPUs) and perf already 
> >>> supports more.
> >>
> >> nice, we're using it all over the place.. how about using bitmap_alloc?
> > 
> > Okay.
> > 
> > The other places is mainly perf record from Alexey's recent affinity changes.
> > These probably need to be fixed.
> > 
> > +Alexey
> 
> Despite the issue indeed looks generic for stat and record modes,
> have you already observed record startup overhead somewhere in your setups?
> I would, first, prefer to reproduce the overhead, to have stable use case 
> for evaluation and then, possibly, improvement.

What I meant the cpu_set usages you added in 

commit 9d2ed64587c045304efe8872b0258c30803d370c
Author: Alexey Budankov <alexey.budankov@linux.intel.com>
Date:   Tue Jan 22 20:47:43 2019 +0300

    perf record: Allocate affinity masks

need to be fixed to allocate dynamically, or at least use MAX_NR_CPUs to
support systems with >1024CPUs. That's an independent functionality
problem.

I haven't seen any large enough perf record usage to run
into the IPI problems for record.

-Andi

  reply	other threads:[~2019-10-23 17:19 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-20 17:51 Optimize perf stat for large number of events/cpus v2 Andi Kleen
2019-10-20 17:51 ` [PATCH v2 1/9] perf evsel: Always preserve errno while cleaning up perf_event_open failures Andi Kleen
2019-10-22  8:01   ` Jiri Olsa
2019-11-12 11:18   ` [tip: perf/core] " tip-bot2 for Andi Kleen
2019-10-20 17:51 ` [PATCH v2 2/9] perf evsel: Avoid close(-1) Andi Kleen
2019-10-22  8:01   ` Jiri Olsa
2019-11-12 11:18   ` [tip: perf/core] " tip-bot2 for Andi Kleen
2019-10-20 17:51 ` [PATCH v2 3/9] perf pmu: Use file system cache to optimize sysfs access Andi Kleen
2019-10-23  9:47   ` Jiri Olsa
2019-10-20 17:51 ` [PATCH v2 4/9] perf affinity: Add infrastructure to save/restore affinity Andi Kleen
2019-10-23  9:59   ` Jiri Olsa
2019-10-23 13:02     ` Andi Kleen
2019-10-23 14:30       ` Jiri Olsa
2019-10-23 14:52         ` Andi Kleen
2019-10-23 16:16           ` Alexey Budankov
2019-10-23 17:19             ` Andi Kleen [this message]
2019-10-23 18:08               ` Alexey Budankov
2019-10-23 22:37                 ` Andi Kleen
2019-10-24  8:46                   ` Alexey Budankov
2019-10-20 17:51 ` [PATCH v2 5/9] perf evsel: Add iterator to iterate over events ordered by CPU Andi Kleen
2019-10-20 17:51 ` [PATCH v2 6/9] perf stat: Use affinity for closing file descriptors Andi Kleen
2019-10-20 17:52 ` [PATCH v2 7/9] perf stat: Use affinity for opening events Andi Kleen
2019-10-20 17:52 ` [PATCH v2 8/9] perf stat: Use affinity for reading Andi Kleen
2019-10-20 17:52 ` [PATCH v2 9/9] perf stat: Use affinity for enabling/disabling events Andi Kleen
2019-10-23 10:30   ` Jiri Olsa
2019-10-23 13:07     ` Andi Kleen
2019-10-22  8:02 ` Optimize perf stat for large number of events/cpus v2 Jiri Olsa
2019-10-22 14:11   ` Arnaldo Carvalho de Melo

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