From: Andrew Morton <akpm@linux-foundation•org>
To: Maxim Uvarov <muvarov@ru•mvista.com>
Cc: linuxppc-dev@ozlabs•org, wli@holomorphy•com, pavel@ucw•cz,
dada1@cosmosbay•com
Subject: Re: [PATCH] Performance Stats: Kernel patch
Date: Thu, 10 May 2007 11:12:42 -0700 [thread overview]
Message-ID: <20070510111242.dd42adae.akpm@linux-foundation.org> (raw)
In-Reply-To: <4642FDD6.5090609@ru.mvista.com>
On Thu, 10 May 2007 11:11:18 +0000 Maxim Uvarov <muvarov@ru•mvista.com> wrote:
> >syscall entry is a super-hotpath and there will be a developer revolt
> >if we go adding an incl to that path, sorry.
> >
> >
> >
> Yes, I know that it is very critical part of code. May be protection with
> ifdef CONFIG_TASKSTATS in all entry.S can be solution?
> In that case we can be sure that nothing wrong can not happen,
> and if this functionality is needed we can turn on this.
I very much hope that all distributors will enable taskstats, so that won't
help.
I don't think the syscall-counting feature has a future, sorry. Perhaps
you could do something like hooking it up on-demand by insertion of a kprobe,
dunno.
> >(Did that incl also cover the int 80 entry?)
> >
> >
> Actually not. But counter increments each time when syscall calls.
> But it is in very save place, just after
> SAVE_ALL
> GET_THREAD_INFO(%ebp)
> So it is very hard to break something.
>
What I meant was: the code appears to be counting sysenter-invoked syscalls,
but it isn't counting not int 80-invoked syscalls.
next prev parent reply other threads:[~2007-05-10 18:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-08 16:26 [PATCH] Performance Stats: Kernel patch Maxim Uvarov
2007-05-08 19:32 ` Andrew Morton
2007-05-10 11:11 ` Maxim Uvarov
2007-05-10 18:12 ` Andrew Morton [this message]
2007-05-11 16:51 ` Maxim Uvarov
2007-05-11 17:23 ` Using kprobes [was " Linas Vepstas
2007-05-12 9:15 ` Christoph Hellwig
2007-05-21 15:28 ` Maxim Uvarov
2007-05-08 23:32 ` Linas Vepstas
2007-05-10 10:22 ` Maxim Uvarov
2007-05-10 16:47 ` Linas Vepstas
-- strict thread matches above, loose matches on Subject: below --
2007-05-10 11:42 Maxim Uvarov
2007-05-10 12:03 ` Pavel Machek
2007-05-10 18:25 ` Andrew Morton
2007-05-10 12:39 Maxim Uvarov
2007-05-10 12:38 ` Josh Boyer
2007-05-10 18:23 ` Maxim Uvarov
2007-05-11 17:13 Maxim Uvarov
2007-05-12 10:39 ` Andrea Righi
2007-05-22 17:19 Maxim Uvarov
2007-05-22 18:48 ` Dave Jones
2007-05-22 20:08 ` Andrew Morton
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