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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 6A855C00A89 for ; Fri, 30 Oct 2020 17:11:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 038012075E for ; Fri, 30 Oct 2020 17:11:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NRTnCr1c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727380AbgJ3RLy (ORCPT ); Fri, 30 Oct 2020 13:11:54 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:55005 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726272AbgJ3RLx (ORCPT ); Fri, 30 Oct 2020 13:11:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604077913; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xYKXOVaB9Lqk7p+DNzbwFvXdhWfTDvuqQ9VGT8imCvs=; b=NRTnCr1cM8+gvfpsMGiR0DOFFp+CGxGH0151jVayg3vhcFtHAtB9ARhNQgCReSpz36Me0I g4qeOa5nh+5ELTYwrK+0fa7ZCbh2IavjnHDaxCjdkR1ZDthtiwAxZWPBrISRY1Cdyk6ie5 q+2fKW3OjX+5sGW0UxsiqR5cKLD02ek= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-178-W7ntctm2N0eOOxax29wTxQ-1; Fri, 30 Oct 2020 13:11:48 -0400 X-MC-Unique: W7ntctm2N0eOOxax29wTxQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B14B4107AFB6; Fri, 30 Oct 2020 17:11:46 +0000 (UTC) Received: from carbon (unknown [10.36.110.25]) by smtp.corp.redhat.com (Postfix) with ESMTP id 204696EF6A; Fri, 30 Oct 2020 17:11:39 +0000 (UTC) Date: Fri, 30 Oct 2020 18:11:38 +0100 From: Jesper Dangaard Brouer To: Peter Zijlstra Cc: mingo@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, linux-kernel@vger.kernel.org, kan.liang@linux.intel.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, ak@linux.intel.com, eranian@google.com, brouer@redhat.com Subject: Re: [PATCH 4/6] perf: Optimize get_recursion_context() Message-ID: <20201030181138.215b2b6a@carbon> In-Reply-To: <20201030151955.187580298@infradead.org> References: <20201030151345.540479897@infradead.org> <20201030151955.187580298@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: On Fri, 30 Oct 2020 16:13:49 +0100 Peter Zijlstra wrote: > "Look ma, no branches!" > > Cc: Jesper Dangaard Brouer > Cc: Steven Rostedt > Signed-off-by: Peter Zijlstra (Intel) > --- Cool trick! :-) Acked-by: Jesper Dangaard Brouer > kernel/events/internal.h | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > --- a/kernel/events/internal.h > +++ b/kernel/events/internal.h > @@ -205,16 +205,15 @@ DEFINE_OUTPUT_COPY(__output_copy_user, a > > static inline int get_recursion_context(int *recursion) > { > - int rctx; > + unsigned int pc = preempt_count(); > + unsigned int rctx = 0; > > - if (unlikely(in_nmi())) > - rctx = 3; > - else if (in_irq()) > - rctx = 2; > - else if (in_serving_softirq()) > - rctx = 1; > - else > - rctx = 0; > + if (pc & (NMI_MASK)) > + rctx++; > + if (pc & (NMI_MASK | HARDIRQ_MASK)) > + rctx++; > + if (pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)) > + rctx++; > > if (recursion[rctx]) > return -1; > > -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer