From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2F8FC433F4 for ; Mon, 27 Aug 2018 08:35:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7CC3208CA for ; Mon, 27 Aug 2018 08:35:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7CC3208CA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727050AbeH0MUk (ORCPT ); Mon, 27 Aug 2018 08:20:40 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33374 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726826AbeH0MUk (ORCPT ); Mon, 27 Aug 2018 08:20:40 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4FBF84021FC6; Mon, 27 Aug 2018 08:34:59 +0000 (UTC) Received: from krava (unknown [10.43.17.209]) by smtp.corp.redhat.com (Postfix) with SMTP id D2C1D2166B41; Mon, 27 Aug 2018 08:34:57 +0000 (UTC) Date: Mon, 27 Aug 2018 10:34:57 +0200 From: Jiri Olsa To: Alexey Budankov Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , Andi Kleen , linux-kernel , linux-perf-users@vger.kernel.org Subject: Re: [PATCH v2 2/2]: perf record: enable asynchronous trace writing Message-ID: <20180827083457.GE24695@krava> References: <54cc11d7-3ef2-c856-052e-6e2c309ff743@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54cc11d7-3ef2-c856-052e-6e2c309ff743@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 27 Aug 2018 08:34:59 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Mon, 27 Aug 2018 08:34:59 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'jolsa@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 23, 2018 at 07:47:01PM +0300, Alexey Budankov wrote: SNIP > diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c > index e71d46cb01cc..c8b921c88a5d 100644 > --- a/tools/perf/util/mmap.c > +++ b/tools/perf/util/mmap.c > @@ -292,11 +292,11 @@ int perf_mmap__read_init(struct perf_mmap *map) > } > > int perf_mmap__push(struct perf_mmap *md, void *to, > - int push(void *to, void *buf, size_t size)) > + int push(void *to, void *buf, size_t size, off_t), off_t *off) > { > u64 head = perf_mmap__read_head(md); > unsigned char *data = md->base + page_size; > - unsigned long size; > + unsigned long size, size0 = 0; > void *buf; > int rc = 0; > > @@ -308,23 +308,22 @@ int perf_mmap__push(struct perf_mmap *md, void *to, > > if ((md->start & md->mask) + size != (md->end & md->mask)) { > buf = &data[md->start & md->mask]; > - size = md->mask + 1 - (md->start & md->mask); > - md->start += size; > - > - if (push(to, buf, size) < 0) { > - rc = -1; > - goto out; > - } > + size0 = md->mask + 1 - (md->start & md->mask); > + md->start += size0; > + memcpy(md->data, buf, size0); > } > > buf = &data[md->start & md->mask]; > size = md->end - md->start; > md->start += size; > + memcpy(md->data + size0, buf, size); this will need more comments.. and explanation why we copy the data over to another buffer.. it's interesting, it's still faster jirka