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From: Ingo Molnar <mingo@elte.hu>
To: Andy Lutomirski <luto@mit.edu>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	John Stultz <johnstul@us.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/6] x86-64: Micro-optimize vclock_gettime
Date: Tue, 29 Mar 2011 08:27:06 +0200	[thread overview]
Message-ID: <20110329062706.GE27398@elte.hu> (raw)
In-Reply-To: <cover.1301324270.git.luto@mit.edu>


* Andy Lutomirski <luto@mit.edu> wrote:

> This series speeds up vclock_gettime(CLOCK_MONOTONIC) on by almost 30%
> (tested on Sandy Bridge).  They're ordered in roughly decreasing order
> of improvement.
> 
> These are meant for 2.6.40, but if anyone wants to take some of them
> for 2.6.39 I won't object.
> 
> The changes and timings (fastest of 20 trials of 100M iters on Sandy
> Bridge) are:
> 
> Unpatched:
> 
> CLOCK_MONOTONIC: 22.09ns
> CLOCK_REALTIME_COARSE: 4.23ns
> CLOCK_MONOTONIC_COARSE: 5.65ns

  [ Patched: ]

> CLOCK_MONOTONIC: 15.66ns
> CLOCK_REALTIME_COARSE: 3.44ns
> CLOCK_MONOTONIC_COARSE: 4.23ns

That looks like a nice speedup, and speedups are definitely welcome. Many of 
your speedup patches were framed in an unclean or hard to maintain fashion 
though - so those have to be improved for this series to become palatable.

Thanks,

	Ingo

  parent reply	other threads:[~2011-03-29  6:27 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-28 15:06 [PATCH 0/6] x86-64: Micro-optimize vclock_gettime Andy Lutomirski
2011-03-28 15:06 ` [PATCH 1/6] x86-64: Optimize vread_tsc's barriers Andy Lutomirski
2011-03-29  6:18   ` Ingo Molnar
2011-03-28 15:06 ` [PATCH 2/6] x86-64: Don't generate cmov in vread_tsc Andy Lutomirski
2011-03-29  6:15   ` Ingo Molnar
2011-03-29 11:52     ` Andrew Lutomirski
2011-03-28 15:06 ` [PATCH 3/6] x86-64: Put vsyscall_gtod_data at a fixed virtual address Andy Lutomirski
2011-03-28 17:49   ` Thomas Gleixner
2011-03-28 18:09     ` Andrew Lutomirski
2011-03-28 21:35     ` Andrew Lutomirski
2011-03-28 23:13       ` Thomas Gleixner
2011-03-28 15:06 ` [PATCH 4/6] x86-64: vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0 Andy Lutomirski
2011-03-29  6:21   ` Ingo Molnar
2011-03-29 11:54     ` Andrew Lutomirski
2011-03-28 15:06 ` [PATCH 5/6] x86-64: Omit frame pointers on vread_tsc Andy Lutomirski
2011-03-29  6:24   ` Ingo Molnar
2011-03-28 15:06 ` [PATCH 6/6] x86-64: Turn off -pg and turn on -foptimize-sibling-calls for vDSO Andy Lutomirski
2011-03-29  6:27 ` Ingo Molnar [this message]
2011-04-06 18:20 ` [PATCH 0/6] x86-64: Micro-optimize vclock_gettime Andi Kleen
2011-04-06 20:10   ` Andrew Lutomirski
2011-04-06 20:14     ` Andi Kleen
2011-04-06 20:49       ` Andrew Lutomirski

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