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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 E3021C43387 for ; Mon, 17 Dec 2018 15:55:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE82A2133F for ; Mon, 17 Dec 2018 15:55:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NzN4oTZi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387964AbeLQPzm (ORCPT ); Mon, 17 Dec 2018 10:55:42 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:39890 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727617AbeLQPzl (ORCPT ); Mon, 17 Dec 2018 10:55:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=574+4ZD7Du9DDrY3jcdjsYd7VDFDIpxaJakuUWbr19s=; b=NzN4oTZi6gyJm2aSWquP3ym0d 9omamrHx6pqwcZKsaR2e90jn3JJGPgWxUbNtXeKUrfjI47HpoiolK5gTOXYmROfIcTsA4j38T2tS6 QwtlKihqL0AwxJKPVt2KhAMOEkNu+c9hCRXVjbXZIp9geLuF9OkitZG5hfKTCJ3BtBmTXjGlrSYI1 4TgSqH4hgpz+eFez7W8mmEGlwcbjR5NRugb3gofnJfLixyB/rnj0dIWTg3Trhfze1lT42vr5lqQVB Z5uHM1LAngIidwmkDDiiTrrPgFICAjkZgEEmZ5miFSveGJjArtzaUovOv2s9v6TQNP94sjT0v0yGT oftNPPBHg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gYvEu-0000Ca-Vq; Mon, 17 Dec 2018 15:55:29 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7717F20276AC4; Mon, 17 Dec 2018 16:55:25 +0100 (CET) Date: Mon, 17 Dec 2018 16:55:25 +0100 From: Peter Zijlstra To: Suren Baghdasaryan Cc: gregkh@linuxfoundation.org, tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com, mingo@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 4/6] psi: introduce state_mask to represent stalled psi states Message-ID: <20181217155525.GC2218@hirez.programming.kicks-ass.net> References: <20181214171508.7791-1-surenb@google.com> <20181214171508.7791-5-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181214171508.7791-5-surenb@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 14, 2018 at 09:15:06AM -0800, Suren Baghdasaryan wrote: > The psi monitoring patches will need to determine the same states as > record_times(). To avoid calculating them twice, maintain a state mask > that can be consulted cheaply. Do this in a separate patch to keep the > churn in the main feature patch at a minimum. > > Signed-off-by: Suren Baghdasaryan > --- > include/linux/psi_types.h | 3 +++ > kernel/sched/psi.c | 29 +++++++++++++++++++---------- > 2 files changed, 22 insertions(+), 10 deletions(-) > > diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h > index 2cf422db5d18..2c6e9b67b7eb 100644 > --- a/include/linux/psi_types.h > +++ b/include/linux/psi_types.h > @@ -53,6 +53,9 @@ struct psi_group_cpu { > /* States of the tasks belonging to this group */ > unsigned int tasks[NR_PSI_TASK_COUNTS]; > > + /* Aggregate pressure state derived from the tasks */ > + u32 state_mask; > + > /* Period time sampling buckets for each state of interest (ns) */ > u32 times[NR_PSI_STATES]; > Since we spend so much time counting space in that line, maybe add a note to the Changlog about how this fits. Also, since I just had to re-count, you might want to add explicit numbers to the psi_res and psi_states enums. > + if (state_mask & (1 << s)) We have the BIT() macro, but I'm honestly not sure that will improve things.