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[2620:137:e000::1:20]) by mx.google.com with ESMTP id u2-20020a17090341c200b001a96b39bb35si15435068ple.439.2023.04.28.00.38.03; Fri, 28 Apr 2023 00:38:14 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=wqx15uW1; dkim=neutral (no key) header.i=@linutronix.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345532AbjD1HaY (ORCPT + 99 others); Fri, 28 Apr 2023 03:30:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345518AbjD1HaW (ORCPT ); Fri, 28 Apr 2023 03:30:22 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C36E26A1; Fri, 28 Apr 2023 00:30:20 -0700 (PDT) Date: Fri, 28 Apr 2023 09:30:16 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1682667018; 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: in-reply-to:in-reply-to:references:references; bh=tN4Is3StFqX6AUDx4ZBtDx5Nj+CllWKd/w/6il3hpyQ=; b=wqx15uW1RLL0CbZDoxYf5ZOThN2vIOeOq2pRMcep3M6h57EQBqS88obhqiWbiw88KViOj6 VA9ReGQc1QdyFAU9Gnu0TvgpcXr2nJoMzLhf67lUeuOCdPETj+rrDQlY595Qk93t3RsRo1 0LM7o3oy4fgT10huAydY8TmBduSwhpCojwWPdG+wd+jyUCw33XwLC//pPeuhftiFBfonp+ 22G7LfpOG5qABkwEuu2FEvauekWlNzGgu2IkD/WHuUCArEEroDybVQZHHhtotts8UvPDLO 1/NqGZlcelpcpp6qqvob0aYwbCWiMEAyuHcRpq5iz2+gWeLztgzNKXOppRs9dA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1682667018; 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: in-reply-to:in-reply-to:references:references; bh=tN4Is3StFqX6AUDx4ZBtDx5Nj+CllWKd/w/6il3hpyQ=; b=CY/OuaBlaNjH98AS9nB9bbKmsmkIbHNhue8djrmt85kZjYTw4OyGfX3OLYI3jiKqaWeXOn oEy3cUiN/9aAPTCA== From: Sebastian Andrzej Siewior To: Kurt Kanzenbach Cc: Jan Kiszka , Thomas Gleixner , "Bouska, Zdenek" , Will Deacon , Catalin Marinas , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-rt-users@vger.kernel.org" , Nishanth Menon , Puranjay Mohan Subject: Re: Unfair qspinlocks on ARM64 without LSE atomics => 3ms delay in interrupt handling Message-ID: <20230428073016.YfrIGGoN@linutronix.de> References: <87pm7qxrg6.ffs@tglx> <19641ab0-ab6a-9af7-8c64-34030e187848@siemens.com> <871qk5782i.fsf@kurt> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <871qk5782i.fsf@kurt> X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023-04-27 15:45:09 [+0200], Kurt Kanzenbach wrote: > > Are we aware of other concrete case where it bites? Even with just > > "normal" contented spin_lock usage? > > Well, some years ago I've observed a similar problem with ARM64 > spinlocks, cpu_relax() and retry loops (in the futex code). It also > generated latency spikes up to 2-3ms. Back then, it was easily > reproducible using stress-ng --ptrace 4. That was fixed by https://patchwork.kernel.org/project/linux-arm-kernel/patch/1399528508-2806-1-git-send-email-arjun.kv@samsung.com if my memory serves me well. > Thanks, > Kurt Sebastian