From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1IiFlr-0000uD-NO for user-mode-linux-devel@lists.sourceforge.net; Wed, 17 Oct 2007 13:45:39 -0700 Received: from saraswathi.solana.com ([198.99.130.12]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1IiFlq-0006H7-4F for user-mode-linux-devel@lists.sourceforge.net; Wed, 17 Oct 2007 13:45:39 -0700 Date: Wed, 17 Oct 2007 16:45:27 -0400 From: Jeff Dike Message-ID: <20071017204527.GB12812@c2.user-mode-linux.org> References: <1f154f440710161936h4800b0c5nb3140ff504212625@mail.gmail.com> <20071017155504.GD9497@c2.user-mode-linux.org> <1f154f440710170916j4fdb857fw40c9b2fd2b66f63f@mail.gmail.com> <20071017171920.GA10388@c2.user-mode-linux.org> <1f154f440710171243x40898f8bq386c91c59789fb42@mail.gmail.com> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <1f154f440710171243x40898f8bq386c91c59789fb42@mail.gmail.com> Subject: Re: [uml-devel] Dramatic drop in C3 state residency with NO_HZ patches List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Hrishikesh Cc: user-mode-linux-devel@lists.sourceforge.net On Wed, Oct 17, 2007 at 03:43:01PM -0400, Hrishikesh wrote: > Ok the straces do seem to tell the story; they follow below: Except they're telling the wrong story: > for the case where is the kernel is patched and NO_HZ enabled, > {it_interval={0, 0}, it_value={0, 91986}}) = 0 > nanosleep({0, 91986000}, {0, 91986000}) = 0 .1 sec > {it_interval={0, 0}, it_value={0, 291955}}) = 0 > nanosleep({0, 291955000}, {0, 291955000}) = 0 .3 sec > {it_interval={0, 0}, it_value={1, 701741}}) = 0 > nanosleep({1, 701741000}, {1, 701741000}) = 0 1.7 sec > for the case where the kernel is patched, but NO_HZ is __not__ enabled, > there is a do_nanosleep() every 100 or so us. > > setitimer(ITIMER_VIRTUAL, {it_interval={0, 0}, it_value={0, 0}}, > {it_interval={0, 0}, it_value={0, 0}}) = 0 > nanosleep({0, 0}, {0, 0}) = 0 This actually looks very broken - it's sleeping for no time, practically a busy-loop. And this case is keeping the host in C3 longer than the second-long sleeps in the first case? Jeff -- Work email - jdike at linux dot intel dot com ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel