From patchwork Mon Dec 16 20:19:00 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: 13910290 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 CE28913D29A for ; Mon, 16 Dec 2024 20:19:31 +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=1734380373; cv=none; b=fQ/cDeZGlOZLEXwXCkILBWNOwTgQ7YDQHVc0njr8h1N+cK4zdD5l9judaEdOXG9vlTJy0/JHtCWGR0c/guKuXkVufvhfE4/1Rkdw87AEz56YIb8kSy8h03RGutiLbLCgSI9gDGRLak6hqc77jevWf7LIg1PhqDQOJPc8JcP+QdM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734380373; c=relaxed/simple; bh=autjX2BFlkh5JX3T6v+m00FmZiBEezDsQc6QmV1Bz9Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MyLPCSAvH6xr9dGOseSPReszALTiIKhZyVsEx9LhVpTNv3TWnalvYzbX/F1NfZY/MIJk1Ov5Xx8JYpZwilPxhyuGCCEe5zcrA+lzT5+zcWsmEyO3b03eCqt3SbDj9aoGAT6mgSHTWbz9kto+NMSQ7erlOgSRwXTGVTBNlF1NK/k= 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=s3cyoOK+; 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="s3cyoOK+" Received: from localhost (localhost [127.0.0.1]) by 009.lax.mailroute.net (Postfix) with ESMTP id 4YBrrg1Nytzlff02; Mon, 16 Dec 2024 20:19:31 +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=1734380367; x=1736972368; bh=x8T0F ciUE7PfSXIZC03uQcBhaMy99ac/QEXSqtplfZc=; b=s3cyoOK+yjVSp8h6jHGuF qY/W9qotQuXl2k05br1FaAoeeU1EQ7JTqJq/aAGyVaaSGqpRHRYnwdrDcQnhiJVH qmuuro5hgwdCNNSp/TkJqO8cgy2D1P2uQ6LnS0Cgj8m8mD4DtUmz+P/ZVYJMPWfo 3Z02a7ecu6kikgtLvsQSsgJw5JfULUV8bHnM2CJ1At+19QqmlWw6F6uNsffb0uV8 4jYk9JC205htkehFfWW+dusj7O0Bqt1szNxbPTF5r6k8mC5Dv7N1/FfmA543AcLY /B/fewKI+SLEoNse2LNL8QpOdASLkp56KqWvkPdQoz3GrPFtPLXxkTs3ep2T5Pc2 Q== 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 SmrjVZWJ_jFh; Mon, 16 Dec 2024 20:19:27 +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 4YBrrH30yPzlff0n; Mon, 16 Dec 2024 20:19:11 +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 1/2] block: Optimize blk_mq_submit_bio() for the cache hit scenario Date: Mon, 16 Dec 2024 12:19:00 -0800 Message-ID: <20241216201901.2670237-2-bvanassche@acm.org> X-Mailer: git-send-email 2.47.1.613.gc27f4b7a9f-goog In-Reply-To: <20241216201901.2670237-1-bvanassche@acm.org> References: <20241216201901.2670237-1-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. Cc: Damien Le Moal Cc: Christoph Hellwig Signed-off-by: Bart Van Assche --- 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);