From: Ben Pfaff Date: Wed, 6 Mar 2013 00:12:21 +0000 (-0800) Subject: timeval: Enable caching the current time even on x86-64. X-Git-Tag: sliver-openvswitch-1.10.90-1~10^2~107 X-Git-Url: http://git.onelab.eu/?a=commitdiff_plain;h=3d6702a2e6253f0561d56e7af6ede84d3b0e9150;p=sliver-openvswitch.git timeval: Enable caching the current time even on x86-64. With CFM enabled on 1000 tunnels, this reduced CPU use from about 30% to about 22%. Bug #15171. Signed-off-by: Ben Pfaff Acked-by: Ethan Jackson --- diff --git a/lib/timeval.h b/lib/timeval.h index 5a7b6e25c..d5c12f065 100644 --- a/lib/timeval.h +++ b/lib/timeval.h @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc. + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -45,18 +45,12 @@ BUILD_ASSERT_DECL(TYPE_IS_SIGNED(time_t)); * much time will be wasted in signal handlers and calls to clock_gettime(). */ #define TIME_UPDATE_INTERVAL 100 -/* True on systems (particularly x86-64 Linux) where clock_gettime() is - * inexpensive. On these systems, we don't bother caching the current time. - * Instead, we consult clock_gettime() directly when needed. - * - * False on systems where clock_gettime() is relatively expensive. On these - * systems, we cache the current time and set up a periodic SIGALRM to remind - * us to update it. - * - * Also false on systems (e.g. ESX) that don't support setting up timers based - * on a monotonically increasing clock. */ +/* True on systems that support a monotonic clock. Compared to just getting + * the value of a variable, clock_gettime() is somewhat expensive, even on + * systems that try hard to optimize it (such as x86-64 Linux), so it's + * worthwhile to minimize calls via caching. */ #ifndef CACHE_TIME -#if defined ESX || (defined __x86_64__ && defined LINUX_DATAPATH) +#if defined ESX #define CACHE_TIME 0 #else #define CACHE_TIME 1