From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp07.in.ibm.com (e28smtp07.in.ibm.com [122.248.162.7]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id EBE721A0313 for ; Tue, 3 Feb 2015 03:12:38 +1100 (AEDT) Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 2 Feb 2015 21:42:35 +0530 Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 116241258060 for ; Mon, 2 Feb 2015 21:43:34 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay01.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t12GCPY154460536 for ; Mon, 2 Feb 2015 21:42:26 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t12GCOim001487 for ; Mon, 2 Feb 2015 21:42:25 +0530 From: "Aneesh Kumar K.V" To: Michael Ellerman , Anton Blanchard Subject: Re: [PATCH] powerpc/mm: Add trace point for tracking hash pte fault In-Reply-To: <1422425467.11009.2.camel@ellerman.id.au> References: <1421753750-17135-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1421809627.4900.1.camel@ellerman.id.au> <87d268v7xm.fsf@linux.vnet.ibm.com> <1422425467.11009.2.camel@ellerman.id.au> Date: Mon, 02 Feb 2015 21:42:21 +0530 Message-ID: <87y4og70nu.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Michael Ellerman writes: > On Wed, 2015-01-21 at 14:15 +0530, Aneesh Kumar K.V wrote: >> Michael Ellerman writes: >> >> > On Tue, 2015-01-20 at 17:05 +0530, Aneesh Kumar K.V wrote: >> >> This enables us to understand how many hash fault we are taking >> >> when running benchmarks. >> >> >> >> For ex: >> >> -bash-4.2# ./perf stat -e powerpc:hash_fault -e page-faults /tmp/ebizzy.ppc64 -S 30 -P -n 1000 >> >> ... >> >> >> >> Performance counter stats for '/tmp/ebizzy.ppc64 -S 30 -P -n 1000': >> >> >> >> 1,10,04,075 powerpc:hash_fault >> >> 1,10,03,429 page-faults >> >> >> >> 30.865978991 seconds time elapsed >> > >> > Looks good. >> > >> > Can you attach some test results that show it's not hurting performance when >> > it's disabled. >> >> ebizzy with -S 30 -t 1 -P gave >> 13627 records/s -> Without patch >> 13546 records/s -> With patch with tracepoint disabled > > OK. So that's about -0.6%. Are we happy with that? I'm not sure. > > Can you do a few more runs and see if that's a stable result. That is within the run variance for that test. Infact I found it difficult to get a stable records/s with ebizzy run, even after fixing the random state variable and forcing single thread. I ended up doing a micro benchmark that allocate a large region and touch one byte per page. That resulted in time perf stat -e page-faults -e powerpc:hash_fault ./a.out Performance counter stats for './a.out': 10,00,062 page-faults 10,00,068 powerpc:hash_fault 12.414350121 seconds time elapsed real 0m12.558s user 0m0.577s sys 0m11.932s and with that test we have an average system time for 10 run Without patch sys: 0m11.2425 With patch: sys: 0m11.3258 ie, a -0.7% impact If that impact is high we could possibly put that tracepoint within #ifdef CONFIG_DEBUG_VM ? -aneesh