[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20090926150103.GB30071@elte.hu>
Date: Sat, 26 Sep 2009 17:01:03 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Ulrich Drepper <drepper@...hat.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Fr??d??ric Weisbecker <fweisbec@...il.com>,
linux kernel <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] perf tools: Dont use openat()
* Eric Dumazet <eric.dumazet@...il.com> wrote:
> Ulrich Drepper a ??crit :
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Eric Dumazet wrote:
> >>> We can certainly remove that reliance - wanna send a patch for it?
> >
> > Come on, the silliness has to stop. The kernel must be recent and to
> > use it adequately the C library also must be recent. And "recent" is
> > not even correct anymore: the functions are available for more then two
> > years. Removing the use of the modern interfaces makes everything
> > slower and might even re-introduce race conditions my patch fixed.
> >
>
> First time I ear that C library *must* be recent. This was never
> mentionned in Documentation/Changes, "Minimal Requirements"
>
> "perf list" can be 100x slower, and even racy, I dont mind. At all.
>
> $ time perf list >/dev/null 2>/dev/null
>
> real 0m0.001s
> user 0m0.000s
> sys 0m0.001s
Yep, doesnt look problematic from a performance POV.
> With openat(), I cannot use "perf" on machines I can only change
> kernel, since changing glibc is too risky for legacy apps. I could use
> static and private glibc, but last time I tried this I lost few hours
> and failed.
Yeah, we generally dont want to force an upgrade of other components if
possible. The fact that you ran into it in a pre -rc1 kernel means that
there's a thousand others out there who will run into similar problems.
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists