From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965948AbZLHT5d (ORCPT ); Tue, 8 Dec 2009 14:57:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965926AbZLHT51 (ORCPT ); Tue, 8 Dec 2009 14:57:27 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:47107 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756239AbZLHT50 (ORCPT ); Tue, 8 Dec 2009 14:57:26 -0500 X-Authority-Analysis: v=1.0 c=1 a=8SZt-bVv9bwA:10 a=20KFwNOVAAAA:8 a=omOdbC7AAAAA:8 a=meVymXHHAAAA:8 a=Q7tOuroGd9pSVVEP3cQA:9 a=bMqyXDSbIQhVsu8Koq8A:7 a=GqzjSsG7p6-IK-TaHUVK0wqFw8EA:4 a=jEp0ucaQiEUA:10 a=jeBq3FmKZ4MA:10 a=1JCLseEUMIDt3x-0:21 a=eeQa0qiLiz2Bz2A4:21 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.89.75 Message-Id: <20091208195731.376084898@goodmis.org> User-Agent: quilt/0.48-1 Date: Tue, 08 Dec 2009 14:54:07 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Frederic Weisbecker , Li Zefan , Lai Jiangshan Subject: [PATCH 2/2][RFC] [PATCH 2/2] tracing: Write directly into splice page for trace_pipe References: <20091208195405.653797300@goodmis.org> Content-Disposition: inline; filename=0002-tracing-Write-directly-into-splice-page-for-trace_pi.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt Now that the trace_seq has a separate buffer space, we can use this feature to write directly into the splice page, instead of writing to the trace_seq buffer and then copying it. This has shown almost a 4% improvement in reading trace_pipe via splice: Average timing of reading 10megs from trace_pipe before patch: real 0m1.619s user 0m0.002s sys 0m1.596s After patch: real 0m1.561s user 0m0.002s sys 0m1.535s These were the average of five runs of reading 10megs. Cc: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 32 +++++--------------------------- 1 files changed, 5 insertions(+), 27 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index df25c4f..0ee4e0e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -468,25 +468,6 @@ ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt) return cnt; } -static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt) -{ - int len; - void *ret; - - if (s->len <= s->readpos) - return -EBUSY; - - len = s->len - s->readpos; - if (cnt > len) - cnt = len; - ret = memcpy(buf, s->buffer + s->readpos, cnt); - if (!ret) - return -EFAULT; - - s->readpos += cnt; - return cnt; -} - /* * ftrace_max_lock is used to protect the swapping of buffers * when taking a max snapshot. The buffers themselves are @@ -3240,21 +3221,18 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, if (!pages[i]) break; - rem = tracing_fill_pipe_page(rem, iter); + trace_seq_init(&iter->seq, page_address(pages[i]), PAGE_SIZE); - /* Copy the data into the page, so we can start over. */ - ret = trace_seq_to_buffer(&iter->seq, - page_address(pages[i]), - iter->seq.len); - if (ret < 0) { + rem = tracing_fill_pipe_page(rem, iter); + if (!iter->seq.len) { __free_page(pages[i]); break; } + partial[i].offset = 0; partial[i].len = iter->seq.len; - - trace_seq_reset(&iter->seq); } + trace_seq_init(&iter->seq, &iter->buffer, FTRACE_SEQ_BUFSIZE); trace_event_read_unlock(); mutex_unlock(&iter->mutex); -- 1.6.5