From patchwork Mon Dec 4 16:51:06 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Nan X-Patchwork-Id: 120571 Delivered-To: patch@linaro.org Received: by 10.140.22.227 with SMTP id 90csp4666931qgn; Mon, 4 Dec 2017 08:53:15 -0800 (PST) X-Google-Smtp-Source: AGs4zMYjt2r+TE4nsiAXX8olv8+03EiKJvrdqMSgBvQ855B2R/LIRoVB2tIrtojcEJzJJOvFLrAO X-Received: by 10.98.33.8 with SMTP id h8mr19852198pfh.160.1512406395330; Mon, 04 Dec 2017 08:53:15 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1512406395; cv=none; d=google.com; s=arc-20160816; b=GasitKLEz3B+jt+ziGzm/3qze8OzkTRZ2kLc3Ymez/EqGxuKvYpdBEiwrUmqbzGYv5 Shml6LS9qzZQKi1OS/plIE6HsgjZcgiMBQSM9+cZOAGzbV48PcG/wm5+gFXKbNGpiHr/ 17sARJMI4u+FqZ1ltblbRrxIoH/5HrBTaXR0dQpjLLF6AXd5P+55H0nZ3Ppgv8Lv8zZd AsIqWJpXjP6d1CUVy/xiqV7oS3wskpwSKMtBM9WEKQFMTqCCP6sbMNwJJjAG8DokswW7 s/3jWljyTcAp1fv4hl+E14823mkAGC+oqsZfpcM+wFCzc7eLvXZJczozJr6/CgED/rLP bkjg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:arc-authentication-results; bh=YPC0++37hdwQ8vN+PoZjJse9jOr8hE105o9adGPD3ao=; b=s6vXUqCB/QWcbXQWdKKILgkeiws0VGEgorftj3tHw7Gomr4Uzgx38rpMR6QsR3DW8F JE+X6dEjh/emi72icVLgbNqno2+NwmxgO9bk+qdc0SsBQntslrcrmG+o2/a2uXEK469P e/4FBDRQ2o7fitiB6omP0Ne1ASPK/PbYgNo8OZ+3/wYdBRtn4jD1yH5RS1NRnvVpF6Wt mJl3NMxYuWFjPik48Vo9TyX1XYWVxwss5vhSJN0lnBHVtNYpuRDuedopIF8x9AAOfbDA /l+QveIa+Zkcw112tIjNFTvdAog41a4Q9PwtI6v06fiHG6yzRJFIEFwsslLuWp+jF2eq chrQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id m6si9993438pln.239.2017.12.04.08.53.15; Mon, 04 Dec 2017 08:53:15 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752707AbdLDQxO (ORCPT + 28 others); Mon, 4 Dec 2017 11:53:14 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:2205 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752362AbdLDQxL (ORCPT ); Mon, 4 Dec 2017 11:53:11 -0500 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 879A96A8B531; Tue, 5 Dec 2017 00:52:57 +0800 (CST) Received: from linux-4hy3.site (10.107.193.248) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.361.1; Tue, 5 Dec 2017 00:52:51 +0800 From: Wang Nan To: , , , , CC: , Wang Nan Subject: [PATCH v3 2/3] perf tools: Don't discard prev in backward mode Date: Mon, 4 Dec 2017 16:51:06 +0000 Message-ID: <20171204165107.95327-3-wangnan0@huawei.com> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20171204165107.95327-1-wangnan0@huawei.com> References: <20171204165107.95327-1-wangnan0@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Perf record can switch output. The new output should only store the data after switching. However, in overwrite backward mode, the new output still have the data from old output. That also brings extra overhead. At the end of mmap_read, the position of processed ring buffer is saved in md->prev. Next mmap_read should be end in md->prev if it is not overwriten. That avoids to process duplicate data. However, the md->prev is discarded. So next mmap_read has to process whole valid ring buffer, which probably include the old processed data. Avoid calling backward_rb_find_range() when md->prev is still available. Signed-off-by: Wang Nan Tested-by: Kan Liang --- tools/perf/util/mmap.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) -- 2.10.1 diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index 3f262e7..5f8cb15 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -267,18 +267,6 @@ static int backward_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 return -1; } -static int rb_find_range(void *data, int mask, u64 head, u64 old, - u64 *start, u64 *end, bool backward) -{ - if (!backward) { - *start = old; - *end = head; - return 0; - } - - return backward_rb_find_range(data, mask, head, start, end); -} - int perf_mmap__push(struct perf_mmap *md, bool backward, void *to, int push(void *to, void *buf, size_t size)) { @@ -290,19 +278,28 @@ int perf_mmap__push(struct perf_mmap *md, bool backward, void *buf; int rc = 0; - if (rb_find_range(data, md->mask, head, old, &start, &end, backward)) - return -1; + start = backward ? head : old; + end = backward ? old : head; if (start == end) return 0; size = end - start; if (size > (unsigned long)(md->mask) + 1) { - WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n"); + if (!backward) { + WARN_ONCE(1, "failed to keep up with mmap data. (warn only once)\n"); - md->prev = head; - perf_mmap__consume(md, backward); - return 0; + md->prev = head; + perf_mmap__consume(md, backward); + return 0; + } + + /* + * Backward ring buffer is full. We still have a chance to read + * most of data from it. + */ + if (backward_rb_find_range(data, md->mask, head, &start, &end)) + return -1; } if ((start & md->mask) + size != (end & md->mask)) {