From patchwork Wed Dec 18 21:22:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bart Van Assche X-Patchwork-Id: 13914164 Received: from 009.lax.mailroute.net (009.lax.mailroute.net [199.89.1.12]) (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 846E11FBE9B for ; Wed, 18 Dec 2024 21:23:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734557000; cv=none; b=knbg99uhTdhiKZW1gyYEG5RrrQKdPzTVirHHH4OeWz96PDgE/rcs/MzLyvZ2uYCvNXHAqyw8zIfxMAv5eDrp/NpbhKXRavtQtJ7Ps5wLIAvYwy9yplyGalr8ycfLhrM0TBYXLcjh8re6c3Ua+ESj+l7VZFmz2MafiasIbqqXqk8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734557000; c=relaxed/simple; bh=+cqSOxM/X75UnO0v7ha9edr48Mcut5PfZpDSq2W9LRA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ug29bUJ1Fx7AJSKEVRrFSa6Lu73lnw3xfsZXhvLqAFSPCA/NUqv2l3QwW2FOIrwYre2KVe54oHMxUXciW1Z1ky9ugE0A3NXNiFtvaKhnA+QT+JsEBW8HWeIEnDkMNJPWFuPQdAQtaWrpvc2AhzpazrEDBxnKbwYipOnptcv7ATg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=UbW3IvFP; arc=none smtp.client-ip=199.89.1.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="UbW3IvFP" Received: from localhost (localhost [127.0.0.1]) by 009.lax.mailroute.net (Postfix) with ESMTP id 4YD69C143Fzlff0B; Wed, 18 Dec 2024 21:23:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:mime-version:references:in-reply-to :x-mailer:message-id:date:date:subject:subject:from:from :received:received; s=mr01; t=1734556988; x=1737148989; bh=NegsF s0MNhSV8qmX3NPaBQfPPKUDrbelZseBCfeFvcI=; b=UbW3IvFPCSN2suqSWaGbT WhpIGcarPpnoo1gTwp2CY5cJhrZhr7kx4gpbCzJ/Kog+iOCRNYyCOoeUyB3FOdaY bJ0yh1y7/o+aSR8ACl4m1JLx2J7nMl2yCKncC+dMNpEjJk6WMsrbV5cwSFCIXRgF f9u5Dhw7MlyBp9lv+tTdenMomIir0yQaNqE9OH4Tm+GMvoSc0upEZO73bfDHhm/s fIRtX8KjhJ+V0RLR90AA2CGKREDivHFBK+AVOcfXG1apiGEKDUgHNHCvqCMA1seG MPymVMmHuBfLeySnVcKqToz7Depq9yseKmtsx+IQ0Wt97imE8fo00NuT0xMCiQoU A== X-Virus-Scanned: by MailRoute Received: from 009.lax.mailroute.net ([127.0.0.1]) by localhost (009.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id 2M7MqjqQpvsd; Wed, 18 Dec 2024 21:23:08 +0000 (UTC) Received: from bvanassche.mtv.corp.google.com (unknown [104.135.204.82]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 009.lax.mailroute.net (Postfix) with ESMTPSA id 4YD6970VRDzlfflC; Wed, 18 Dec 2024 21:23:06 +0000 (UTC) From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Damien Le Moal , Bart Van Assche Subject: [PATCH v3 1/2] block: Reorder the request allocation code in blk_mq_submit_bio() Date: Wed, 18 Dec 2024 13:22:45 -0800 Message-ID: <20241218212246.1073149-2-bvanassche@acm.org> X-Mailer: git-send-email 2.47.1.613.gc27f4b7a9f-goog In-Reply-To: <20241218212246.1073149-1-bvanassche@acm.org> References: <20241218212246.1073149-1-bvanassche@acm.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Help the CPU branch predictor in case of a cache hit by handling the cache hit scenario first. Reviewed-by: Damien Le Moal Cc: Christoph Hellwig Signed-off-by: Bart Van Assche Reviewed-by: Christoph Hellwig --- block/blk-mq.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 7ee21346a41e..8d2aab4d9ba9 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3102,12 +3102,12 @@ void blk_mq_submit_bio(struct bio *bio) goto queue_exit; new_request: - if (!rq) { + if (rq) { + blk_mq_use_cached_rq(rq, plug, bio); + } else { rq = blk_mq_get_new_requests(q, plug, bio, nr_segs); if (unlikely(!rq)) goto queue_exit; - } else { - blk_mq_use_cached_rq(rq, plug, bio); } trace_block_getrq(bio);