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AJvYcCV3k4/WKJ3UVoANImTPRXQdwLbDhq002/e955weZx2po8MipfyN1rBVET9o3y6M81E+G5cyfNkgxD+sBQ==@vger.kernel.org X-Received: by 2002:a17:903:2984:b0:2b0:5ae9:ee4 with SMTP id d9443c01a7336-2b269aa3b7emr63373955ad.5.1775114251507; Thu, 02 Apr 2026 00:17:31 -0700 (PDT) X-Received: by 2002:a17:903:2984:b0:2b0:5ae9:ee4 with SMTP id d9443c01a7336-2b269aa3b7emr63373715ad.5.1775114251087; Thu, 02 Apr 2026 00:17:31 -0700 (PDT) Received: from sumit_ws.dhcp.broadcom.net ([192.19.234.250]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b27477c54bsm24612825ad.27.2026.04.02.00.17.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Apr 2026 00:17:30 -0700 (PDT) From: Sumit Saxena To: martin.petersen@oracle.com, axboe@kernel.dk Cc: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, mpi3mr-linuxdrv.pdl@broadcom.com, James Rizzo , Sumit Saxena Subject: [PATCH 2/3] block: align nr_active_requests_shared_tags to avoid cache line contention Date: Thu, 2 Apr 2026 13:16:36 +0530 Message-ID: <20260402074637.92417-3-sumit.saxena@broadcom.com> X-Mailer: git-send-email 2.43.7 In-Reply-To: <20260402074637.92417-1-sumit.saxena@broadcom.com> References: <20260402074637.92417-1-sumit.saxena@broadcom.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e From: James Rizzo Place nr_active_requests_shared_tags on its own cache line so it does not share a cache line with nr_requests and other hot fields, avoiding significant performance hits from false sharing on some CPU architectures. Signed-off-by: James Rizzo Signed-off-by: Sumit Saxena --- include/linux/blkdev.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index d463b9b5a0a5..7ed566c81c1b 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -561,7 +561,9 @@ struct request_queue { struct timer_list timeout; struct work_struct timeout_work; - atomic_t nr_active_requests_shared_tags; + /* ensure nr_active_requests_shared_tags and nr_requests are on different cache lines + to avoid significant performance hits on cache line contention on some CPU architectures */ + atomic_t nr_active_requests_shared_tags ____cacheline_aligned_in_smp; struct blk_mq_tags *sched_shared_tags; -- 2.43.7