From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 76582 invoked by alias); 26 Aug 2016 18:39:46 -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 76567 invoked by uid 89); 26 Aug 2016 18:39:45 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=Hx-spam-relays-external:sk:bzq-79-, H*r:sk:bzq-79-, H*RU:sk:bzq-79-, H*MI:sk:7a45c7b X-HELO: mail-wm0-f51.google.com Received: from mail-wm0-f51.google.com (HELO mail-wm0-f51.google.com) (74.125.82.51) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 26 Aug 2016 18:39:35 +0000 Received: by mail-wm0-f51.google.com with SMTP id i5so4425857wmg.0 for ; Fri, 26 Aug 2016 11:39:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=98xLiqZKthh+bakufQ9kvFlu63moeQLHXwva5n4S9CM=; b=GumBLaRtglcrjFI1ZELr4FmZKqRdr9tVk+bKu93TVEooNTOarSlCSbFTmQUscHmxRQ t9YaE4MhZRrIxHESgqH2ue3Eph97OMBFPY5uFx7gg0a/ItDqzGxHsGDYZfCBq5m7ne+K ylxvrK+ekQ5dTksiUf9xNvy2p3PUuogVHKl14r2tVU/avb4ypX2RYrfnmhue5WF+7xB6 0zq8U6bwtniVIrFfju7kWIH3HFFjUSaXCqIUiQEa1JOx2r2m1aGt015lKtKUN1wOK/2l wToemB2lV1yT3U3Z/goSBbobroAl0103JIwmuKOuUgsw8ry/h8D0SFrruTLrvcRzqPPD TBRg== X-Gm-Message-State: AE9vXwNzTyC4tk9WDiwgVzFxyEvorYVCMFdxq2IPg7It64CyNoYRoqGU0hWNW19I8L0oAQ== X-Received: by 10.194.89.129 with SMTP id bo1mr5420875wjb.105.1472236773298; Fri, 26 Aug 2016 11:39:33 -0700 (PDT) Received: from [10.0.0.5] (bzq-79-180-158-23.red.bezeqint.net. [79.180.158.23]) by smtp.googlemail.com with ESMTPSA id 190sm267517wmk.13.2016.08.26.11.39.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Aug 2016 11:39:32 -0700 (PDT) Subject: Re: Some newbie questions To: David Smith , "Frank Ch. Eigler" References: <91592a2a-7373-6a27-413c-cf4aca70cb76@scylladb.com> <20160810164742.GF13748@redhat.com> <382185d7-86d6-45d0-1855-d7e3c1639083@scylladb.com> <42a5bad6-c094-cb7a-6f89-a592367ca30b@scylladb.com> <20160811161845.GC12190@redhat.com> <8af2d587-ebc0-730b-3b1c-a452c486af57@scylladb.com> <20160817183537.GB4647@redhat.com> <7a45c7b4-59b9-e0f8-77a5-d7ce3634fcfc@redhat.com> Cc: Mark Wielaard , systemtap@sourceware.org From: Avi Kivity Message-ID: <0d91a649-873b-6d89-a5ef-ae88d11ce588@scylladb.com> Date: Fri, 26 Aug 2016 18:39:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <7a45c7b4-59b9-e0f8-77a5-d7ce3634fcfc@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-q3/txt/msg00210.txt.bz2 On 08/25/2016 08:37 PM, David Smith wrote: > On 08/25/2016 11:21 AM, Avi Kivity wrote: >> Hi, >> >> Should I wait for ongoing improvement here, or shall I look elsewhere >> for my tracing needs? >> >> It would be a pity (for me) if I have to find another solution, because >> systemtap has all the expressiveness and integration I need. But it has >> a dramatic impact on my application runtime. >> >> I was able to extract some useful data with perf probe/perf record, but >> as soon as I need to qualify a probe point with runtime information, >> perf falls short. > As Frank mentioned in a previous email, it might be possible for us to > switch to using straight kprobes instead of syscall tracing to handle > mmap tracing. In your use case of calling epoll_wait() lots of times per > second, that might be a *big* win. > > I'll see what can be done to add that feature. > Thanks a lot. I'll be happy to test patches.