Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932415AbWEQBok (ORCPT ); Tue, 16 May 2006 21:44:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932421AbWEQBoj (ORCPT ); Tue, 16 May 2006 21:44:39 -0400 Received: from mail05.syd.optusnet.com.au ([211.29.132.186]:18873 "EHLO mail05.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S932415AbWEQBoj (ORCPT ); Tue, 16 May 2006 21:44:39 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17514.32708.282431.544415@wombat.chubb.wattle.id.au> Date: Wed, 17 May 2006 11:43:32 +1000 From: Peter Chubb To: Andi Kleen Cc: Peter Chubb , Arnd Bergmann , Martin Peschke , Andrew Morton , linux-kernel@vger.kernel.org, hch@infradead.org, arjan@infradead.org, James.Smart@emulex.com, James.Bottomley@steeleye.com Subject: Re: [RFC] [Patch 7/8] statistics infrastructure - exploitation prerequisite In-Reply-To: <200605170327.52605.ak@suse.de> References: <446A1023.6020108@de.ibm.com> <200605170103.08917.arnd@arndb.de> <17514.31511.386806.484792@wombat.chubb.wattle.id.au> <200605170327.52605.ak@suse.de> X-Mailer: VM 7.17 under 21.4 (patch 17) "Jumbo Shrimp" XEmacs Lucid Comments: Hyperbole mail buttons accepted, v04.18. X-Face: GgFg(Z>fx((4\32hvXq<)|jndSniCH~~$D)Ka:P@e@JR1P%Vr}EwUdfwf-4j\rUs#JR{'h# !]])6%Jh~b$VA|ALhnpPiHu[-x~@<"@Iv&|%R)Fq[[,(&Z'O)Q)xCqe1\M[F8#9l8~}#u$S$Rm`S9% \'T@`:&8>Sb*c5d'=eDYI&GF`+t[LfDH="MP5rwOO]w>ALi7'=QJHz&y&C&TE_3j! Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1016 Lines: 24 >>>>> "Andi" == Andi Kleen writes: Anrd> - do_gettimeofday potentially slow, reliable TOD clock, Anrd> microsecond resolution >> Slow, not necessarily safe to call in IRQ context. Andi> It's only slow if the platform can't do better. On good hardware Andi> it is fast. And yes it is safe to call in IRQ Andi> context. Networking does that all the time. Thanks for the clarification. I measured do_gettimeofday on IA64 at around 120 cycles (mind you that was some time ago now, before the last lot of time function revisions in the kernel). Whether that's slow or not depends on your application. -- Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au http://www.ertos.nicta.com.au ERTOS within National ICT Australia - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/