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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 B4F39C433F4 for ; Mon, 27 Aug 2018 09:12:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77301204EC for ; Mon, 27 Aug 2018 09:12:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 77301204EC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.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 S1727488AbeH0M6k (ORCPT ); Mon, 27 Aug 2018 08:58:40 -0400 Received: from mga07.intel.com ([134.134.136.100]:58054 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726809AbeH0M6k (ORCPT ); Mon, 27 Aug 2018 08:58:40 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Aug 2018 02:12:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,294,1531810800"; d="scan'208";a="68389495" Received: from linux.intel.com ([10.54.29.200]) by orsmga008.jf.intel.com with ESMTP; 27 Aug 2018 02:12:38 -0700 Received: from [10.125.252.155] (abudanko-mobl.ccr.corp.intel.com [10.125.252.155]) by linux.intel.com (Postfix) with ESMTP id 7C0B95803DA; Mon, 27 Aug 2018 02:12:35 -0700 (PDT) Subject: Re: [PATCH v2 2/2]: perf record: enable asynchronous trace writing To: Jiri Olsa Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Namhyung Kim , Andi Kleen , linux-kernel , linux-perf-users@vger.kernel.org References: <54cc11d7-3ef2-c856-052e-6e2c309ff743@linux.intel.com> <20180827083457.GE24695@krava> From: Alexey Budankov Organization: Intel Corp. Message-ID: <8afd6aaf-45ec-e477-78bd-83b6c99da713@linux.intel.com> Date: Mon, 27 Aug 2018 12:12:34 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180827083457.GE24695@krava> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 27.08.2018 11:34, Jiri Olsa wrote: > 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 Sure. Comments will follow in v3. We copy data into a buffer to release space in the kernel buffer as fast as possible. That lets the kernel to store more data earlier than other per-cpu buffers are handled. > > jirka >