From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Andy Lutomirski <luto@MIT.EDU>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
Ingo Molnar <mingo@elte.hu>, Andi Kleen <andi@firstfloor.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v3 5/6] x86-64: Move vread_tsc into a new file with sensible options
Date: Tue, 10 May 2011 16:36:02 +0200 [thread overview]
Message-ID: <1305038162.2914.93.camel@laptop> (raw)
In-Reply-To: <84f1b1e345955d38309678d578ccdff9de6eca7b.1305035945.git.luto@mit.edu>
On Tue, 2011-05-10 at 10:15 -0400, Andy Lutomirski wrote:
> vread_tsc is short and hot, and it's userspace code so the usual
> reasons to keep frame pointers around, enable -pg, and turn off
> sibling calls don't apply.
>
I really don't like that, turning off frame pointers here means that if
your profiler interrupt hits while in the vDSO the user-space backtrace
is dead.
Please leave the frame pointer in. Esp on x86_64 the cost of keeping the
framepointer isn't much at all since it isn't nearly as register starved
as i386.
I'm fine with stripping -pg, that is indeed useless for the vDSO.
next prev parent reply other threads:[~2011-05-10 14:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-10 14:15 [PATCH v3 0/6] Micro-optimize vclock_gettime Andy Lutomirski
2011-05-10 14:15 ` [PATCH v3 1/6] x86-64: Clean up vdso/kernel shared variables Andy Lutomirski
2011-05-10 14:48 ` Borislav Petkov
2011-05-12 11:16 ` Andrew Lutomirski
2011-05-10 14:15 ` [PATCH v3 2/6] x86-64: Remove unnecessary barrier in vread_tsc Andy Lutomirski
2011-05-10 14:15 ` [PATCH v3 3/6] x86-64: Don't generate cmov " Andy Lutomirski
2011-05-10 14:15 ` [PATCH v3 4/6] x86-64: vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0 Andy Lutomirski
2011-05-10 14:15 ` [PATCH v3 5/6] x86-64: Move vread_tsc into a new file with sensible options Andy Lutomirski
2011-05-10 14:36 ` Peter Zijlstra [this message]
2011-05-10 14:15 ` [PATCH v3 6/6] x86-64: Turn off -pg and turn on -foptimize-sibling-calls for vDSO Andy Lutomirski
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