From: Andi Kleen <ak@suse.de>
To: Brent Casavant <bcasavan@sgi.com>
Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au
Subject: Re: [PATCH] Add kallsyms_lookup() result cache
Date: Sat, 19 Jun 2004 00:03:26 +0200 [thread overview]
Message-ID: <20040619000326.067c3ff6.ak@suse.de> (raw)
In-Reply-To: <Pine.SGI.4.58.0406181435570.5029@kzerza.americas.sgi.com>
On Fri, 18 Jun 2004 15:03:00 -0500
Brent Casavant <bcasavan@sgi.com> wrote:
> On 2.6 based systems, the top command utilizes /proc/[pid]/wchan to
> determine WCHAN symbol name information. This information is provided
> by the kernel function kallsyms_lookup(), which expands a stem-compressed
That sounds more like a bug in your top to me. /proc/*/wchan itself
does not access kallsyms, it just outputs a number.
My top doesn't do that.
Are you saying your top reads /proc/kallsyms on each redisplay?
That sounds completely wrong - it should only read the file once
and cache it and then look the numbers it is reading from wchan
in the cache.
Doing the cache in the kernel is the wrong place. This should be fixed
in user space.
As an unrelated comment: i would suggest to avoid rwlocks until
absolutely needed. They are a lot slower than regular spinlocks.
-Andi
next prev parent reply other threads:[~2004-06-18 22:07 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-18 20:03 [PATCH] Add kallsyms_lookup() result cache Brent Casavant
2004-06-18 20:37 ` Martin Josefsson
2004-06-18 20:55 ` Brent Casavant
2004-06-18 22:03 ` Andi Kleen [this message]
2004-06-18 23:26 ` Jesse Barnes
2004-06-18 23:56 ` Andi Kleen
2004-06-19 0:16 ` Jesse Barnes
2004-06-18 23:31 ` Brent Casavant
2004-06-18 23:59 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2004-06-19 0:43 Albert Cahalan
2004-06-19 4:51 ` Herbert Xu
2004-06-19 12:03 ` Albert Cahalan
2004-06-19 10:06 ` Andrew Morton
2004-06-19 13:05 ` Albert Cahalan
2004-06-22 19:45 ` Brent Casavant
2004-06-22 20:10 ` Jesse Barnes
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