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 38461C77B61 for ; Fri, 28 Apr 2023 07:37:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345543AbjD1Hha (ORCPT ); Fri, 28 Apr 2023 03:37:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345542AbjD1HhX (ORCPT ); Fri, 28 Apr 2023 03:37:23 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B88BC30D2; Fri, 28 Apr 2023 00:37:06 -0700 (PDT) From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1682667425; 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=U9WgFT6n38IbKIlQOmRg7Aj71yFL8oXTEMGMk9PC1UU=; b=4cSn329b8crefnSTA47d1YI2emkxVXGgguXlqtN2Wp8x7S3EABWu4LPYFv2FEPTDSsjyHD WTy0bAEotQqU5tSC5Yw06aKQ7l3Ro954/ZW65469u6ZVnTEjirukDvNVsPAaXvRQoNElGf 4OtiAsL+w0qYioL1IMZ9WoLPoO/QfXG/BvIdvCHIurH27LAl4HrpLIrfkr5icm7Uo/9hYJ uyKhw23ef9gNCNy3Kwtn4SbJ8Eue6eT3jYW2/vWc4nrBXvZG93FIa0IghYP+v5YbyGY+/n vFRXlNO0NvulCqVw53OLVxXW8OIwziwfom4zFMlTrubMKeufkL2piiHlXZjfMg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1682667425; 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=U9WgFT6n38IbKIlQOmRg7Aj71yFL8oXTEMGMk9PC1UU=; b=0NVjNxMxzO/mkLIYy1+la/dShvTTc27qDJDa4p65qQm2vG+r0BixN76776jRsYB/0q1n5R /TENqNceTv5iILAQ== To: Sebastian Andrzej Siewior 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 In-Reply-To: <20230428073016.YfrIGGoN@linutronix.de> References: <87pm7qxrg6.ffs@tglx> <19641ab0-ab6a-9af7-8c64-34030e187848@siemens.com> <871qk5782i.fsf@kurt> <20230428073016.YfrIGGoN@linutronix.de> Date: Fri, 28 Apr 2023 09:37:03 +0200 Message-ID: <87wn1wv4o0.fsf@kurt> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Fri Apr 28 2023, Sebastian Andrzej Siewior wrote: > 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? >>=20 >> 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/1399528508-2= 806-1-git-send-email-arjun.kv@samsung.com > > if my memory serves me well. We've had a different processor, but yes, we configured CPUACTLR_EL1[31] to 1 in U-Boot to avoid any kernel modifications. Maybe it helps here too? Thanks, Kurt [1] - https://developer.arm.com/documentation/100095/0003/way1382037666700 --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJHBAEBCgAxFiEEvLm/ssjDfdPf21mSwZPR8qpGc4IFAmRLd58THGt1cnRAbGlu dXRyb25peC5kZQAKCRDBk9HyqkZzghlXD/9HotVNhvqmh29BsoK7Zt1eNEca4+Tq PNmh6Z/fPe9JXwJEiGem1AChnVN7gCao2L+C5nk7ebRqMGyfeHbHqnRz5Fa39efr OqZcnmhMMQXLWDt5uu/5t7pdqoOfk1IxHS+FtV7G6IxRuxg/Dp/0t08g0vGJ+PmB I/NvybCd3A4SiUWHuykMyGRl8T/xdqCCtbA8zJae+nfDDo+2lTzGBdZ6u6muB3E8 rWFPXyGH2aULr0Kg3YZvnwVAH8220dRP5LDMxRaxpbmsJcLHvXeJVdAw4A1Mlz0K 6Wl0JUn6SLwQOS26sjEhpVobiKs6g21Dbau0+edD277rIu0VbT6lPi59QwuPQXyI X6pbw+rOe29Gm6fbIuqRzjzzw87AOXw/I0sVc6JvqdT0jWw+YR74IJjD0wsT5/I7 7cn0dMrDcnH5clLWiHZtvbsyjgRmzxYNOrQIuhg86fM3T6N7AY0RXgUk+1WpWjYY h7CG63oQ+RxONCrlpuZyDQSZsdVT7dRbC8Dbr1Avl/zrecrT7AjX4brxNnsSVyVb 5Jr+J1x+QNu4uBkZCoFQ6rZmI+nOsvOXt5M55+sfAuAZx3OZ79CsNlD8GdfHCC3d PGezbfQQzNqgNv/QvFnBSCnQ1tC1exWIrgaJKwsNO80vX/Fya8wjWqUZWchw8skb XakiSUjjvjgN/A== =1+7y -----END PGP SIGNATURE----- --=-=-=--