From: Andi Kleen <andi@firstfloor.org>
To: Raghavendra D Prabhu <rprabhu@wnohang.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>, Andy Lutomirski <luto@mit.edu>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: [RFT/PATCH v2 2/6] x86-64: Optimize vread_tsc's barriers
Date: Fri, 8 Apr 2011 00:52:08 +0200 [thread overview]
Message-ID: <20110407225208.GD21838@one.firstfloor.org> (raw)
In-Reply-To: <20110407214307.GA6449@Xye>
> If only one lfence or serializing instruction is to be used, can't we
> just use RDTSCP instruction (X86_FEATURE_RDTSCP,available only in >=
> i7's and AMD) which both provides TSC as well as an upward serializing
RDTSCP is a full synchronization, much heavier and slower than LFENCE
(or even two of them) Besides it doesn't exist on older CPUs.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2011-04-07 22:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-07 2:03 [RFT/PATCH v2 0/6] Micro-optimize vclock_gettime Andy Lutomirski
2011-04-07 2:03 ` [RFT/PATCH v2 1/6] x86-64: Clean up vdso/kernel shared variables Andy Lutomirski
2011-04-07 8:08 ` Ingo Molnar
2011-04-07 2:03 ` [RFT/PATCH v2 2/6] x86-64: Optimize vread_tsc's barriers Andy Lutomirski
2011-04-07 8:25 ` Ingo Molnar
2011-04-07 11:44 ` Andrew Lutomirski
2011-04-07 15:23 ` Andi Kleen
2011-04-07 17:28 ` Ingo Molnar
2011-04-07 16:18 ` Linus Torvalds
2011-04-07 16:42 ` Andi Kleen
2011-04-07 17:20 ` Linus Torvalds
2011-04-07 18:15 ` Andi Kleen
2011-04-07 18:30 ` Linus Torvalds
2011-04-07 21:26 ` Andrew Lutomirski
2011-04-08 17:59 ` Andrew Lutomirski
2011-04-09 11:51 ` Ingo Molnar
2011-04-07 21:43 ` Raghavendra D Prabhu
2011-04-07 22:52 ` Andi Kleen [this message]
2011-04-07 2:04 ` [RFT/PATCH v2 3/6] x86-64: Don't generate cmov in vread_tsc Andy Lutomirski
2011-04-07 7:54 ` Ingo Molnar
2011-04-07 11:25 ` Andrew Lutomirski
2011-04-07 2:04 ` [RFT/PATCH v2 4/6] x86-64: vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0 Andy Lutomirski
2011-04-07 7:57 ` Ingo Molnar
2011-04-07 11:27 ` Andrew Lutomirski
2011-04-07 2:04 ` [RFT/PATCH v2 5/6] x86-64: Move vread_tsc into a new file with sensible options Andy Lutomirski
2011-04-07 2:04 ` [RFT/PATCH v2 6/6] x86-64: Turn off -pg and turn on -foptimize-sibling-calls for vDSO Andy Lutomirski
2011-04-07 8:03 ` Ingo Molnar
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