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 5389EC433F5 for ; Mon, 27 Aug 2018 08:38:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 173CC20846 for ; Mon, 27 Aug 2018 08:38:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 173CC20846 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 S1727110AbeH0MYg (ORCPT ); Mon, 27 Aug 2018 08:24:36 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38648 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726802AbeH0MYf (ORCPT ); Mon, 27 Aug 2018 08:24:35 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 843C88573A; Mon, 27 Aug 2018 08:38:54 +0000 (UTC) Received: from krava (unknown [10.43.17.209]) by smtp.corp.redhat.com (Postfix) with SMTP id 230112027056; Mon, 27 Aug 2018 08:38:53 +0000 (UTC) Date: Mon, 27 Aug 2018 10:38:52 +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: <20180827083852.GF24695@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 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 27 Aug 2018 08:38:54 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 27 Aug 2018 08:38:54 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.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 > static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evlist, > bool overwrite) > { > u64 bytes_written = rec->bytes_written; > - int i; > - int rc = 0; > + int i, rc = 0; > struct perf_mmap *maps; > + int trace_fd = rec->session->data->file.fd; > + struct aiocb **mmap_aio = rec->evlist->mmap_aio; > + int mmap_aio_size = 0; > + off_t off; > > if (!evlist) > return 0; > @@ -546,14 +620,17 @@ static int record__mmap_read_evlist(struct record *rec, struct perf_evlist *evli > if (overwrite && evlist->bkw_mmap_state != BKW_MMAP_DATA_PENDING) > return 0; > > + off = lseek(trace_fd, 0, SEEK_CUR); > + with async write, do we need to query/set the offset like this all the time? could we just keep/update the offset value in the 'struct perf_data_file' and skip both lseek calls? jirka SNIP > > + record__mmap_read_sync(trace_fd, mmap_aio, mmap_aio_size, rec); > + > + lseek(trace_fd, off, SEEK_SET); > +