From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>,
mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org,
tglx@linutronix.de, linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/core] perf/x86/intel: Clean-up/reduce PEBS code
Date: Mon, 16 Sep 2013 18:03:11 +0200 [thread overview]
Message-ID: <20130916160311.GW18242@two.firstfloor.org> (raw)
In-Reply-To: <20130916060736.GN21832@twins.programming.kicks-ass.net>
> There already was an implicit division there, and
> sizeof(pebs_record_hsw) = 176, can it really optimize that constant
> division?
Yes it can (if nothing else then by converting it to * 1/x)
The only exception is with -Os, but if you want performance
you should not be using that anyways.
You could do that manually, but it's easiest to just keep
the code paths separate and let the compiler worry about it.
> I suppose we could go and introduce CONFIG_PERF_DEBUG and stuff sanity
> checks under that.. :/
Hmm, it's not a sanity check?
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
prev parent reply other threads:[~2013-09-16 16:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-12 18:04 [tip:perf/core] perf/x86/intel: Clean-up/reduce PEBS code tip-bot for Peter Zijlstra
2013-09-14 6:18 ` Andi Kleen
2013-09-16 6:07 ` Peter Zijlstra
2013-09-16 6:17 ` H. Peter Anvin
2013-09-16 7:24 ` Peter Zijlstra
2013-09-16 16:09 ` Andi Kleen
2013-09-16 16:03 ` Andi Kleen [this message]
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