From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3618 invoked by alias); 27 Aug 2009 00:32:40 -0000 Received: (qmail 3610 invoked by uid 22791); 27 Aug 2009 00:32:40 -0000 X-SWARE-Spam-Status: No, hits=-1.8 required=5.0 tests=AWL,BAYES_00,SARE_MSGID_LONG40,SPF_PASS X-Spam-Check-By: sourceware.org Received: from smtp-out.google.com (HELO smtp-out.google.com) (216.239.33.17) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 27 Aug 2009 00:32:35 +0000 Received: from spaceape11.eur.corp.google.com (spaceape11.eur.corp.google.com [172.28.16.145]) by smtp-out.google.com with ESMTP id n7R0WVtO019363 for ; Thu, 27 Aug 2009 01:32:32 +0100 Received: from qyk14 (qyk14.prod.google.com [10.241.83.142]) by spaceape11.eur.corp.google.com with ESMTP id n7R0W2Op005652 for ; Wed, 26 Aug 2009 17:32:29 -0700 Received: by qyk14 with SMTP id 14so324986qyk.17 for ; Wed, 26 Aug 2009 17:32:29 -0700 (PDT) MIME-Version: 1.0 Received: by 10.224.24.80 with SMTP id u16mr5779090qab.75.1251333142290; Wed, 26 Aug 2009 17:32:22 -0700 (PDT) In-Reply-To: <200908262108.49085.pedro@codesourcery.com> References: <7e6c8d660907081308r13bff580rdcf4822c77df8403@mail.gmail.com> <200908251944.45977.pedro@codesourcery.com> <200908262108.49085.pedro@codesourcery.com> Date: Thu, 27 Aug 2009 00:46:00 -0000 Message-ID: Subject: Re: [RFA] Use data cache for stack accesses From: Doug Evans To: Pedro Alves Cc: gdb-patches@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-System-Of-Record: true X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2009-08/txt/msg00466.txt.bz2 On Wed, Aug 26, 2009 at 1:08 PM, Pedro Alves wrote: >> > Did you post number showing off the improvements from >> > having the cache on? =A0E.g., when doing foo, with cache off, >> > I get NNN memory reads, while with cache off, we get only >> > nnn reads. =A0I'd be curious to have some backing behind >> > "This improves remote performance significantly". >> >> For a typical gdb/gdbserver connection here a backtrace of 256 levels >> went from 48 seconds (average over 6 tries) to 4 seconds (average over >> 6 tries). > > Nice! =A0Were all those single runs started from cold cache, or > are you starting from a cold cache and issuing 6 backtraces in > a row? =A0I mean, how sparse were those 6 tries? =A0Shall one > read that as 48,48,48,48,48,48 vs 20,1,1,1,1,1 (some improvement > due to chunking, and large improvement due to caching in following > repeats of the command); or 48,48,48,48,48,48 vs 4,4,4,4,4,4 (large > improvement due to chunking --- caching not actually measured)? The cache was always flushed between backtraces, so that's 48, 48. ..., 48 vs 4, 4, ..., 4. Backtraces win from both chunking and caching. Even in one backtrace gdb will often fetch the same value multiple times. I haven't computed the relative win.