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=-1.0 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 72CA5C43441 for ; Fri, 9 Nov 2018 01:07:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B65E20840 for ; Fri, 9 Nov 2018 01:07:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3B65E20840 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net 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 S1727528AbeKIKpf (ORCPT ); Fri, 9 Nov 2018 05:45:35 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:40540 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727288AbeKIKpf (ORCPT ); Fri, 9 Nov 2018 05:45:35 -0500 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::cf9]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 1DC971475AF01; Thu, 8 Nov 2018 17:07:22 -0800 (PST) Date: Thu, 08 Nov 2018 17:07:21 -0800 (PST) Message-Id: <20181108.170721.825832647693654935.davem@davemloft.net> To: jolsa@redhat.com Cc: acme@kernel.org, linux-kernel@vger.kernel.org, namhyung@kernel.org, jolsa@kernel.org Subject: Re: [PATCH RFC] hist lookups From: David Miller In-Reply-To: <20181108071303.GB29732@krava> References: <20181107194344.GA29732@krava> <20181107.120154.1747291861102322855.davem@davemloft.net> <20181108071303.GB29732@krava> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 08 Nov 2018 17:07:22 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jiri Olsa Date: Thu, 8 Nov 2018 08:13:03 +0100 > we could separated fork/mmaps to separate dummy event map, or just > parse them out in the read thread and create special queue for them > and drop just samples in case we are behind What you say at the end here is basically what I am proposing. Perf dequeues events from mmap ring as fast as possible. Perf has two internal queues, high priority and low priority. High priority events are never dropped. Low priority events are dropped on overload, oldest first.