From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC189155300; Fri, 29 Nov 2024 21:27:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.255.230.98 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732915647; cv=none; b=X2UDa639qHUy8b7owrEAsM8RaBSwYr9MrjWtzA3uIq6/JKkMZV1ZDFePW1dKiXzymsspEKc+Wkd/e0zgWA4+WReWUhBbuNxRxQPumTN5Qq8+qSEpvbE2hMOVB2M+1YXXj5WFgMfGnzp/RlF832TnCUUZ5ztB1MEVhak4ehknkjI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732915647; c=relaxed/simple; bh=76sfWPPa1/SV8pCOjiE3xLXocvoPaWYuIf/151AEDKM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ccPu6NWhsmX1jGnt7oI6GnoH4WxB4tU9rU+KQA4+EsTUo7Y7m3xRWz3u0F6o1GcAWbKvlYXuZqZO2sUQCAtsqQJOvYIhcSRC++4R/ENU+5t02f7t4QyCPMjJ+phDR0bosZdmHkJXzNf10eKYf6OvxR5RYQ+BGalG9CpsvDQvwzk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=denx.de; spf=fail smtp.mailfrom=denx.de; arc=none smtp.client-ip=46.255.230.98 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=denx.de Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=denx.de Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 0064A1C00A0; Fri, 29 Nov 2024 22:27:22 +0100 (CET) Date: Fri, 29 Nov 2024 22:27:22 +0100 From: Pavel Machek To: Sasha Levin Cc: Pavel Machek , Borislav Petkov , linux-kernel@vger.kernel.org, stable@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, puwen@hygon.cn, seanjc@google.com, kim.phillips@amd.com, jmattson@google.com, babu.moger@amd.com, peterz@infradead.org, rick.p.edgecombe@intel.com, brgerst@gmail.com, ashok.raj@intel.com, mjguzik@gmail.com, jpoimboe@kernel.org, nik.borisov@suse.com, aik@amd.com, vegard.nossum@oracle.com, daniel.sneddon@linux.intel.com, acdunlap@google.com, Erwan Velu Subject: Re: [PATCH AUTOSEL 5.15 11/12] x86/barrier: Do not serialize MSR accesses on AMD Message-ID: References: <20240115232718.209642-1-sashal@kernel.org> <20240115232718.209642-11-sashal@kernel.org> <20241128115924.GAZ0hbHKsbtCixVqAe@fat_crate.local> <20241128164310.GCZ0idnhjpAV6wFWm6@fat_crate.local> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PGrglMEykJLBTiqn" Content-Disposition: inline In-Reply-To: --PGrglMEykJLBTiqn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > > - Serious issues as reported by a user of a distribution kernel may= also > > > be considered if they fix a notable performance or interactivity = issue. > > >=20 > > > It sounds like what's going on here, no? > >=20 > > Is it? I'd not expect this to be visible in anything but > > microbenchmarks. Do you have user reports hitting this? > >=20 > > It is not like this makes kernel build 10% slower, is it? >=20 > On Fri, Nov 29, 2024 at 10:30:11AM +0100, Erwan Velu wrote: > > This patch greatly impacts servers on production with AMD systems that > > have lasted since 5.11, having it backported really improves systems > > performance. > > Since this patch, I can share that our database team is no longer > > paged during the night, that's a real noticeable impact. Ok, looks like I misjudged the performance impact, sorry for the noise. Best regards, Pavel --=20 DENX Software Engineering GmbH, Managing Director: Erika Unter HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --PGrglMEykJLBTiqn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCZ0oxugAKCRAw5/Bqldv6 8tkRAKCDcLBQwYzUDwLQIFV1f/3wtwtYJgCggPRpP6HEjgSWs2/FjPCzRtOnb7M= =20C0 -----END PGP SIGNATURE----- --PGrglMEykJLBTiqn--