From: Andrew Morton <akpm@linux-foundation•org>
To: Maxim Uvarov <muvarov@ru•mvista.com>
Cc: linuxppc-dev@ozlabs•org, LKML <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] Performance Stats: Kernel patch
Date: Tue, 22 May 2007 13:08:24 -0700 [thread overview]
Message-ID: <20070522130824.a78976aa.akpm@linux-foundation.org> (raw)
In-Reply-To: <20070522171950.23728.95735.stgit@localhost.localdomain>
On Tue, 22 May 2007 17:19:52 +0000
Maxim Uvarov <muvarov@ru•mvista.com> wrote:
> Sorry for bothering you. I know you are very busy but could
> you please tell me what is situation of this patch?
I'd like to add the context-switch accounting to the taskstats payload.
As we'd then need to uprev the taskstats payload and version it makes sense
to have a look around, see if there's anything else which should be in
there but got missed.
I don't think we can accept the number-of-syscalls accounting feature. It
adds a memory increment into the kernel's number-one hotpath. Something
which people like to obsessively microbenchmark.
And as I said earlier, a 32-bit counter can be overflowed in mere seconds,
so that needs to become 64-bit, in which case we add a memory increment and
a test-n-branch to that hottest path.
There _is_ some cumulative overhead here, and I don't see how the value of
the syscall counter can justify it.
next prev parent reply other threads:[~2007-05-22 20:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-22 17:19 [PATCH] Performance Stats: Kernel patch Maxim Uvarov
2007-05-22 18:48 ` Dave Jones
2007-05-22 20:08 ` Andrew Morton [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-05-11 17:13 Maxim Uvarov
2007-05-12 10:39 ` Andrea Righi
2007-05-10 12:39 Maxim Uvarov
2007-05-10 12:38 ` Josh Boyer
2007-05-10 18:23 ` Maxim Uvarov
2007-05-10 11:42 Maxim Uvarov
2007-05-10 12:03 ` Pavel Machek
2007-05-10 18:25 ` Andrew Morton
2007-05-08 16:26 Maxim Uvarov
2007-05-08 19:32 ` Andrew Morton
2007-05-10 11:11 ` Maxim Uvarov
2007-05-10 18:12 ` Andrew Morton
2007-05-11 16:51 ` Maxim Uvarov
2007-05-08 23:32 ` Linas Vepstas
2007-05-10 10:22 ` Maxim Uvarov
2007-05-10 16:47 ` Linas Vepstas
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