From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794215126; b=r7UB7NWcmUD/4wYgZvFOMXG2iIxJTH9ADxEgRJFjB/FM+EYo2zYD4Evfu8f3CAyP6KzS pTxK83LfS/2r1RGQg3liDP6gH5mBmx5vunDi7cKga79JcwM3Ri+PqB9hDJgKjwR+jh0ni 4w8MiccBLkdJLrRRhn/nwJat5y3DaIPpi8tCjimoYswdAIVNlQPlPEegdvaU48uK9A+Jo /fUYE+FM0OYku6wcT5MbQ7dgtCitVImOK9erU3t6K1G8ww0rVZ3pfSINptMd98iYY0tDk gSODgFSJFHkVGoNPRb8SPGk3UZA7qzTeqIdOmTzUBUCcuGvHaGeHUBDbC784irKVkQw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794215126; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=ddwtRStrJOI7ltMx3bJ8U+RW9zhPc6/v8M8LvxaWFCY=; b=uWWVVfC9HjY/foKHv8n0mTtV6j+tPEfncmHN0m85yItlnEptutE1ahbo1rtjm9hNgLcj 7kd2jj4z1p7zMiYETQepfGGeii72byspeRHn68rFc81gupq/V9cU01H3eU66FEHeIb9Eb hrEO09CzVmqeK2v/hEEIs+wrHpSmnpKONAu/S5L5y6fP1AYddgO7aJ4WfPvIfCT15jsU7 jBuBHt6/kM+gizoRX8uKOBOQeGi32L3vG4XOvGoxvcComou15oqv5iS3+0j8sCTTspNuK 1DA1yZUHFtIorgBP0R7jsFavdG0sU8o0PuMTr3R02H9uTzks8j/app+6enC1odsaCMg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CjTab6cu; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 62C6B606A339 for ; Mon, 9 Nov 2026 09:05:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CjTab6cu Received: by smtp.kernel.org (Postfix) with ESMTPSA id F35A31F008A6; Mon, 9 Nov 2026 09:05:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794215126; bh=ddwtRStrJOI7ltMx3bJ8U+RW9zhPc6/v8M8LvxaWFCY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=CjTab6cu9O371OdjhvlODWLKQ9JBhDEenwq3Ewjuc7UJ9Owcb0lTB/FFCzuWDB1I4 etuOym7wETkK8Dc5wbhoDHQFIisbdje7LrDwsuZuA9ou8SpTBzXGSYNI/Ne31vZiwx WZInLsnAU9H6iSEoohQPBDBQ5iSel1mrxaL3kn0o6kktG56EOVO3ku0BTFSQhOTzvT lhfDul1k60t0a0rhWlY1EdFPS/mKWgcTuxC+tJux7NgSAp0WzOPDcAbnYqJn603qj9 ke2eaD7LB8AhpRHa6lznKDvHxuoEReJ8C1jCfD1g8GTSZP2H2KYb4JAY4zswOqnVQv EBa4tqRbYYLaA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 10/14] s390/sclp_cmd: Replace page allocator calls with kzalloc() Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TWlrZSBSYXBvcG9ydCAoTWljcm9zb2Z0KQ==?= Cc: linux-s390@vger.kernel.org, "Heiko Carstens" , "Vasily Gorbik" , "Alexander Gordeev" , "Christian Borntraeger" In-Reply-To: <20261108-s390-sclp-ready-v1-10-3e7c90eb6676@kernel.org> References: <20261108-s390-sclp-ready-v1-0-3e7c90eb6676@kernel.org> <20261108-s390-sclp-ready-v1-10-3e7c90eb6676@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 09 Nov 2026 09:05:25 +0000 X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > _sclp_get_core_info(), do_chp_configure() and sclp_chp_read_info() > allocate the SCCBs used to read the CPU information, to configure a > channel path and to read the channel path information. >=20 > These buffers can be allocated with kmalloc() as there's nothing special > about them to go directly to the page allocator. >=20 > kmalloc() provides a better API that does not require ugly casts and > kfree() does not need to know the size of the freed object. >=20 > Performance difference between kmalloc() and __get_free_pages() is not > measurable as both allocators take an object/page from a per-CPU list for > fast path allocations. >=20 > For the slow path the performance is anyway determined by the amount of > reclaim involved rather than by what allocator is used. >=20 > While on it, allocate only the amount of memory the SCCB actually > requires in _sclp_get_core_info() rather than rounding it up to the next > power of two. An SCCB must be page aligned and kmalloc() guarantees that > the alignment of an allocation is at least its largest power of two > divisor, so the extended SCCB is still page aligned. >=20 > Replace use of __get_free_pages() and get_zeroed_page() with kzalloc() > and free_page[s]() with kfree(). >=20 > Link: https://lore.kernel.org/all/635405e4-9423-4a25-a6e7-e03c8ea0bcbe@re= dhat.com > Signed-off-by: Mike Rapoport (Microsoft) Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261108-s390-sclp-= ready-v1-0-3e7c90eb6676@kernel.org?part=3D10