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Fri, 4 Nov 2022 21:38:03 +0900 (KST) Received: from epsmtrp1.samsung.com (unknown [182.195.40.13]) by epcas5p4.samsung.com (KnoxPortal) with ESMTPA id 20221104112442epcas5p4dab9270f5d970618f1a13cc39e26016a~kXfg6A5KJ2575525755epcas5p4p; Fri, 4 Nov 2022 11:24:42 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20221104112442epsmtrp1fad3fa115f866fde0a516a82885f4774~kXfg5ZxxI1354313543epsmtrp1d; Fri, 4 Nov 2022 11:24:42 +0000 (GMT) X-AuditID: b6c32a49-a41ff700000006ae-6b-636507abd8c5 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id 4B.34.18644.A76F4636; Fri, 4 Nov 2022 20:24:42 +0900 (KST) Received: from test-zns.sa.corp.samsungelectronics.net (unknown [107.110.206.5]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20221104112441epsmtip2bbe2c1a62732a9a2af633a18186dbe73~kXff2P5H00272702727epsmtip22; Fri, 4 Nov 2022 11:24:41 +0000 (GMT) From: Ankit Kumar To: axboe@kernel.dk Cc: fio@vger.kernel.org, vincentfu@gmail.com, Ankit Kumar Subject: [PATCH 2/2] doc: update about sqthread_poll Date: Fri, 4 Nov 2022 16:43:14 +0530 Message-Id: <20221104111314.25535-3-ankit.kumar@samsung.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221104111314.25535-1-ankit.kumar@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrKKsWRmVeSWpSXmKPExsWy7bCmpu4a9tRkg5kSFmuu/Ga3WH23n83i 46wXzBYb2gQdWDx2zrrL7nH5bKlH35ZVjB6fN8kFsERl22SkJqakFimk5iXnp2TmpdsqeQfH O8ebmhkY6hpaWpgrKeQl5qbaKrn4BOi6ZeYA7VNSKEvMKQUKBSQWFyvp29kU5ZeWpCpk5BeX 2CqlFqTkFJgU6BUn5haX5qXr5aWWWBkaGBiZAhUmZGdcOq5TcI+34v+fWawNjH+4uhg5OSQE TCTu9i1iArGFBHYzSqz/LNfFyAVkf2KUONX1khnC+cwo0fb6EStMx/Kz81khErsYJb5272GE aG9lkuiYKwViswloS7x6e4MZxBYREJbY39HKAmIzC4RKnLz2hR3EFgYa9PnwXrA4i4CqxIOV z8HO4BWwkbhys5cRYpm8xOoNB4DmcHBwCthKbDshDxFexS6xcQI7hO0iMeHsGihbWOLV8S1Q tpTEy/42KDtbYtPDn0wQdoHEkRe9zBC2vUTrqX6w8cwCmhLrd+lDhGUlpp5axwRxMZ9E7+8n UK28EjvmwdiqEn/v3WaBsKUlbr67CmV7SEx8fJkREjwTGCVWb+5gmcAoNwthxQJGxlWMkqkF xbnpqcWmBYZ5qeXwGEvOz93ECE5PWp47GO8++KB3iJGJg/EQowQHs5II76dtyclCvCmJlVWp RfnxRaU5qcWHGE2BwTeRWUo0OR+YIPNK4g1NLA1MzMzMTCyNzQyVxHkXz9BKFhJITyxJzU5N LUgtgulj4uCUamDa1v2wyV1f6kSr/vLrlucSRJXvCz5g+MZ35dimZUtlRNdWFim1/2Y+ud5i 7vvkxQ5HJgUK7di68vhTY5O6TOO/dxNDD2zOndA1s9/YOXb3iaop2/vXqirxBnTHnL/IfK/i wI4vExpvGxyttLt5NmFiFGfU9MbQa8mNXHk3rGacZJit+GdW5cbui9Uh2xJ1LgU5Naj+3XB5 vqjBtx9KdR/epapu5z229/tSTX+GNa8f1r74pLHik9vCPw8fun2aYO/Rm3Hz0HGX+Hkaf9my xfkblt4+9D65+YfEogN6t1+pxwQveXGmv7S22bv11l0DzlKWOdYeaY2vTdbvvvHnSWanyIRK bje7Gxen3pE4ZHdypxJLcUaioRZzUXEiABPG0U3YAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrHJMWRmVeSWpSXmKPExsWy7bCSvG7Vt5Rkg6nH1S3WXPnNbrH6bj+b xcdZL5gtNrQJOrB47Jx1l93j8tlSj74tqxg9Pm+SC2CJ4rJJSc3JLEst0rdL4Mq4dFyn4B5v xf8/s1gbGP9wdTFyckgImEgsPzuftYuRi0NIYAejxMGr59i7GDmAEtISC9cnQtQIS6z895wd oqaZSeLv9EWsIAk2AW2JV29vMIPYIkBF+ztaWUBsZoFwiekHJjOC2MJACz4f3gsWZxFQlXiw 8jkTiM0rYCNx5WYvI8QCeYnVGw4wg+zlFLCV2HZCHiQsBFSyctFklgmMfAsYGVYxSqYWFOem 5xYbFhjlpZbrFSfmFpfmpesl5+duYgQHkZbWDsY9qz7oHWJk4mA8xCjBwawkwvtpW3KyEG9K YmVValF+fFFpTmrxIUZpDhYlcd4LXSfjhQTSE0tSs1NTC1KLYLJMHJxSDUypzYr9oasOVX0Q 9rVq11t4Pz1D4W3vtRvRHxyOeRq92WjUy2UszRvfsiP4Xba4RuIW/0l/a1cW619IN/K8tlXi e+nqv2+K2xcc2/100hYvmVMXMtkXSc3M6W840fHYypd3wh2zhrlfll6r2aXtcjNh3d40O40I ZZt5+89drzeJj54gIDOT00DPumLTCfdKRnG90qp/W3l//Nv0Y2URu/rG47W/J8xYqNTSuPBW TsmTPXw+bZeVfq3muM2fxv1zbt/9HVOvMD/alprd+Ez5+snMZWaPLz2PUPy8UHb6Rf3nBpzK ncb8SgW/naeYe8QXpZopbvNkSUkNuHmx+P0Gz7lpAt/3djjpB1vs2fnguZQSS3FGoqEWc1Fx IgB530/nkQIAAA== X-CMS-MailID: 20221104112442epcas5p4dab9270f5d970618f1a13cc39e26016a X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: REQ_APPROVE CMS-TYPE: 105P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20221104112442epcas5p4dab9270f5d970618f1a13cc39e26016a References: <20221104111314.25535-1-ankit.kumar@samsung.com> Precedence: bulk List-ID: X-Mailing-List: fio@vger.kernel.org Update that when sqthread_poll is enabled the submission and completion latencies reported may not be accurate. This is because the actual submission is done by the kernel polling thread. Signed-off-by: Ankit Kumar --- HOWTO.rst | 4 +++- fio.1 | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/HOWTO.rst b/HOWTO.rst index 0fb5593e..dea625fe 100644 --- a/HOWTO.rst +++ b/HOWTO.rst @@ -2299,7 +2299,9 @@ with the caveat that when used on the command line, they must come after the kernel of available items in the SQ ring. If this option is set, the act of submitting IO will be done by a polling thread in the kernel. This frees up cycles for fio, at the cost of using more CPU in the - system. + system. The submission and completion latencies reported may not be + accurate as fio has no idea when the kernel polling thread submits the + actual I/O. .. option:: sqthread_poll_cpu : [io_uring] [io_uring_cmd] diff --git a/fio.1 b/fio.1 index 4324a975..95c5ce55 100644 --- a/fio.1 +++ b/fio.1 @@ -2090,7 +2090,9 @@ sqthread_poll option. Normally fio will submit IO by issuing a system call to notify the kernel of available items in the SQ ring. If this option is set, the act of submitting IO will be done by a polling thread in the kernel. This frees up cycles for fio, at -the cost of using more CPU in the system. +the cost of using more CPU in the system. The submission and completion +latencies reported may not be accurate as fio has no idea when the kernel +polling thread submits the actual I/O. .TP .BI (io_uring,io_uring_cmd)sqthread_poll_cpu When `sqthread_poll` is set, this option provides a way to define which CPU -- 2.17.1