From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 48482 invoked by alias); 11 May 2018 19:25:58 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 48325 invoked by uid 89); 11 May 2018 19:25:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.6 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=highly X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 11 May 2018 19:25:55 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 610F6EBFFE for ; Fri, 11 May 2018 19:25:54 +0000 (UTC) Received: from segfault.boston.devel.redhat.com (segfault.boston.devel.redhat.com [10.19.60.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 542952026DEF; Fri, 11 May 2018 19:25:54 +0000 (UTC) Received: by segfault.boston.devel.redhat.com (Postfix, from userid 3734) id B16C4B97CE; Fri, 11 May 2018 15:25:53 -0400 (EDT) From: Jeff Moyer To: systemtap@sourceware.org Cc: Jeff Moyer Subject: [PATCH 2/3] io_submit.stp: use an accumulator for traces Date: Fri, 11 May 2018 19:25:00 -0000 Message-Id: <20180511192552.12849-3-jmoyer@redhat.com> In-Reply-To: <20180511192552.12849-1-jmoyer@redhat.com> References: <20180511192552.12849-1-jmoyer@redhat.com> X-SW-Source: 2018-q2/txt/msg00061.txt.bz2 On very large systems, we get a lot of skipped probes due to lock contention on the traces array. The end result is that we don't get any data for such systems. Simply converting the traces array to an accumulator resolves this issue in testing (on a highly- loaded 288 cpu system). Signed-off-by: Jeff Moyer --- testsuite/systemtap.examples/io/io_submit.stp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/testsuite/systemtap.examples/io/io_submit.stp b/testsuite/systemtap.examples/io/io_submit.stp index c5edd66..62d15c9 100755 --- a/testsuite/systemtap.examples/io/io_submit.stp +++ b/testsuite/systemtap.examples/io/io_submit.stp @@ -37,7 +37,7 @@ probe syscall.io_submit.return { */ probe kernel.function("schedule") { if (tid() in in_iosubmit) { - traces[backtrace()]++ + traces[backtrace()] <<< 1 /* * change this to if (1) if you want a backtrace every time @@ -59,7 +59,7 @@ probe kernel.function("schedule") { */ probe end { foreach (stack in traces- limit 30) { - printf("%d:", traces[stack]) + printf("%d:", @count(traces[stack])) print_syms(stack); } } -- 2.8.2.335.g4bb51ae