linux-kernel - Re: [PATCH v5 0/8] perf report: Add latency and parallelism profiling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z6UGJuL5e5WQQL-M@tassilo>
Date: Thu, 6 Feb 2025 10:57:42 -0800
From: Andi Kleen <ak@...ux.intel.com>
To: Dmitry Vyukov <dvyukov@...gle.com>
Cc: namhyung@...nel.org, irogers@...gle.com,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH v5 0/8] perf report: Add latency and parallelism profiling

On Thu, Feb 06, 2025 at 07:41:00PM +0100, Dmitry Vyukov wrote:
> On Thu, 6 Feb 2025 at 19:30, Andi Kleen <ak@...ux.intel.com> wrote:
> >
> > Dmitry Vyukov <dvyukov@...gle.com> writes:
> >
> > > There are two notions of time: wall-clock time and CPU time.
> > > For a single-threaded program, or a program running on a single-core
> > > machine, these notions are the same. However, for a multi-threaded/
> > > multi-process program running on a multi-core machine, these notions are
> > > significantly different. Each second of wall-clock time we have
> > > number-of-cores seconds of CPU time.
> >
> > I'm curious how does this interact with the time / --time-quantum sort key?
> >
> > I assume it just works, but might be worth checking.
> 
> I will check later. But if you have some concrete commands to try, it
> will help. I never used --time-quantum before.

perf report --sort time,overhead,sym 

It just slices perf.data into time slices so you get a time series
instead of full aggregation.

--time-quantum is optional, but sets the slice length,

> > >  tools/perf/util/symbol_conf.h                 |   8 +-
> >
> > We traditionally didn't do it, but in general test coverage
> > of perf report is too low, so I would recommend to add some simple
> > test case in the perf test scripts.
> 
> What of this is testable within the current testing framework?

You can write a shell script that runs it and does 
some basic sanity checking. tests/shell has a lot of examples.

If you don't do that someone will break it like it happened 
to some of my features :/

> Also how do I run tests? I failed to figure it out.

Just "perf test"


-Andi