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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D2A0C61D90 for ; Tue, 21 Nov 2023 16:16:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230374AbjKUQQU (ORCPT ); Tue, 21 Nov 2023 11:16:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229749AbjKUQQS (ORCPT ); Tue, 21 Nov 2023 11:16:18 -0500 Received: from mail-yb1-xb32.google.com (mail-yb1-xb32.google.com [IPv6:2607:f8b0:4864:20::b32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AC22194 for ; Tue, 21 Nov 2023 08:16:15 -0800 (PST) Received: by mail-yb1-xb32.google.com with SMTP id 3f1490d57ef6-d9beb865a40so5379676276.1 for ; Tue, 21 Nov 2023 08:16:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1700583374; x=1701188174; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=X7132CXfUB1dIK7Gmp7xy1yfmtHIvsYahpiV3MBz0a0=; b=GP/UPil69kydzqFR/hqtFscKDaQbzKReKFtFme1qlG2Yxy+1vPzF6cxPT40968hAn+ Fsa9jfaRM0B7V0mYD1nQljQEW0DXDAgnvdeatlX4az6frMQdM026ofn9PF3GllanBx+o aqX8bTFJ8Qhnrp+37EN1S/XXzjpawnUPb6ldq5c6tU56Ku38wcLmPCWO9Wfyw6boGNTv jju4IOfTwPoeCqgwO39pQFE/HYubslzIHTs6MyZk2BOEIZB7JsCCa6UE60KLyKCl/RvV ALEF6E55HzSHasOBzAjnzehFyHrvjY9RZGH3BuzxvVXMHV4VKZYqfDSaNBsPUyiCEVC/ gPxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1700583374; x=1701188174; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=X7132CXfUB1dIK7Gmp7xy1yfmtHIvsYahpiV3MBz0a0=; b=QuNN7g11PaU13YNpq+M+ZgRAevMDO9/7Qd60UCft/msN951JQVBN6QAEBPTMJeRg/4 ztpO7p3f38MpXbpMNUvA6iHyXesMa2xRvbAJq1KomA25mXhtdlR8Yb4ow1aSNIYBzNMB W0RzG3GQqqfLLU/93G6u0XgmJy3epst42BE6xk2A1yKlQXsrb7YyjcmJu+NmpHsnd6uJ UobTlNC81CqhCYzhRr/hN2HxNFDOp8e73oa6MtOGdIqbdFjR6pvpDhSL5tgirwaXH+oA LPrSmkIGbdR04eFPTXQswRddldCLnLHbH98NzgQbtfidVGh/mHQILNOCJkYvmjVEoLsp 2btQ== X-Gm-Message-State: AOJu0Ywh47GoMevP4niJO8OcpwiqQB8zTSN19rqc4RUr8Vuhfyhyiw5E eDYiDO/PvkxBEJfHIyH43qd1oHWaFLV1bw== X-Google-Smtp-Source: AGHT+IGi9uK16aYMAYQhI90N2Dt00CS1k9ov+suyCQkx5en9XvS7iOSQ5LAGauyh7JBmkqcgxMMsew== X-Received: by 2002:a5b:351:0:b0:daf:686c:4919 with SMTP id q17-20020a5b0351000000b00daf686c4919mr10494867ybp.18.1700583374213; Tue, 21 Nov 2023 08:16:14 -0800 (PST) Received: from localhost ([2601:344:8301:57f0:e005:b808:45e:1b60]) by smtp.gmail.com with ESMTPSA id j4-20020a258b84000000b00d9a3fe483cfsm773101ybl.23.2023.11.21.08.16.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Nov 2023 08:16:13 -0800 (PST) Date: Tue, 21 Nov 2023 08:16:13 -0800 From: Yury Norov To: Will Deacon Cc: linux-kernel@vger.kernel.org, Mark Rutland , linux-arm-kernel@lists.infradead.org, Jan Kara , Mirsad Todorovac , Matthew Wilcox , Rasmus Villemoes , Andy Shevchenko , Maxim Kuvyrkov , Alexey Klimov Subject: Re: [PATCH 07/34] perf/arm: optimize opencoded atomic find_bit() API Message-ID: References: <20231118155105.25678-1-yury.norov@gmail.com> <20231118155105.25678-8-yury.norov@gmail.com> <20231121155344.GB1938@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231121155344.GB1938@willie-the-truck> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 21, 2023 at 03:53:44PM +0000, Will Deacon wrote: > On Sat, Nov 18, 2023 at 07:50:38AM -0800, Yury Norov wrote: > > Switch subsystem to use atomic find_bit() or atomic iterators as > > appropriate. > > > > Signed-off-by: Yury Norov > > --- > > drivers/perf/arm-cci.c | 23 +++++------------------ > > drivers/perf/arm-ccn.c | 10 ++-------- > > drivers/perf/arm_dmc620_pmu.c | 9 ++------- > > drivers/perf/arm_pmuv3.c | 8 ++------ > > 4 files changed, 11 insertions(+), 39 deletions(-) > > > > diff --git a/drivers/perf/arm-cci.c b/drivers/perf/arm-cci.c > > index 61de861eaf91..70fbf9d09d37 100644 > > --- a/drivers/perf/arm-cci.c > > +++ b/drivers/perf/arm-cci.c > > @@ -320,12 +320,8 @@ static int cci400_get_event_idx(struct cci_pmu *cci_pmu, > > return CCI400_PMU_CYCLE_CNTR_IDX; > > } > > > > - for (idx = CCI400_PMU_CNTR0_IDX; idx <= CCI_PMU_CNTR_LAST(cci_pmu); ++idx) > > - if (!test_and_set_bit(idx, hw->used_mask)) > > - return idx; > > - > > - /* No counters available */ > > - return -EAGAIN; > > + idx = find_and_set_bit(hw->used_mask, CCI_PMU_CNTR_LAST(cci_pmu) + 1); > > CCI400_PMU_CNTR0_IDX is defined as 1, so isn't this wrong? You're right. Will fix in v2 > [...] > > > diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c > > index 30cea6859574..e41c84dabc3e 100644 > > --- a/drivers/perf/arm_dmc620_pmu.c > > +++ b/drivers/perf/arm_dmc620_pmu.c > > @@ -303,13 +303,8 @@ static int dmc620_get_event_idx(struct perf_event *event) > > end_idx = DMC620_PMU_MAX_COUNTERS; > > } > > > > - for (idx = start_idx; idx < end_idx; ++idx) { > > - if (!test_and_set_bit(idx, dmc620_pmu->used_mask)) > > - return idx; > > - } > > - > > - /* The counters are all in use. */ > > - return -EAGAIN; > > + idx = find_and_set_next_bit(dmc620_pmu->used_mask, end_idx, start_idx); > > It might just be me, but I'd find this a tonne easier to read if you swapped > the last two arguments around so that the offset came before the limit in > the new function. I personally agree, but we already have find_next_*_bit(addr, nbits, offset) functions, and having atomic versions of the same with different order of arguments will make it even more messy... Thanks, Yury