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Tue, 14 Sep 2021 06:08:36 +0000 (GMT) From: "Kiwoong Kim" To: , , , , , , , , , , , , Subject: Question about cmd_queue Date: Tue, 14 Sep 2021 15:08:36 +0900 Message-ID: <000001d7a92e$f4688800$dd399800$@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AdepLrlIqY/QqB7AQZSxee8N2kqb0Q== Content-Language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrOJsWRmVeSWpSXmKPExsWy7bCmmW6qjUOiwbJHEhYnn6xhs3gwbxub xcufV9ksDj7sZLH4uvQZq8Wn9ctYLVYvfsBisejGNiaLy7vmsFl0X9/BZrH8+D8mi667Nxgt lv57y+LA63G5r5fJY/Gel0weExYdYPT4vr6DzePj01ssHn1bVjF6fN4k59F+oJspgCMqxyYj NTEltUghNS85PyUzL91WyTs43jne1MzAUNfQ0sJcSSEvMTfVVsnFJ0DXLTMH6GYlhbLEnFKg UEBicbGSvp1NUX5pSapCRn5xia1SakFKToGhYYFecWJucWleul5yfq6VoYGBkSlQZUJORtfW jawFp7kq1l/5yNTAuJaji5GTQ0LAROL3pu+MXYxcHEICOxglllx6zgzhfGKU2LLnLROE841R YubvfUwwLW/fzIVK7GWU6H/VyArhvGCU6G1+zghSxSagLTHt4W6whIjADSaJTfe3g7ULCyhK rF/2ggXEZhFQldg9pZsVxOYVsJRY+/o6C4QtKHFy5hMwmxlo0LKFr5khVitI/Hy6DKxeREBP 4tKfS2wQNSISszvbwA6XEFjLIbFx+lNGiAYXiTm3+1kgbGGJV8e3sEPYUhKf3+1lg7DrJfZN bWCFaO5hlHi67x9Us7HErGftQDYH0AZNifW79EFMCQFliSO3oG7jk+g4/JcdIswr0dEmBNGo LPFr0mSoIZISM2/egdrqIbFjzWZwMAgJxErcPPqUZQKjwiwkH89C8vEsJJ/NQrhhASPLKkax 1ILi3PTUYqMCI+To3sQITtFabjsYp7z9oHeIkYmD8RCjBAezkgjvtje2iUK8KYmVValF+fFF pTmpxYcYTYFxMJFZSjQ5H5gl8kriDU2NzMwMLE0tTM2MLJTEec+/tkwUEkhPLEnNTk0tSC2C 6WPi4JRqYFKuDa91qnlw9+LTVxcF/rXrtdeWf3qzIjomZaGlS/erJ5INt+a3vea+OGH3qQQj sSPq9xi5ZmZbiD27EG2gcWeRk1dK89x3nt4xyz+5pxhvffF6/byij5dU+5IucJpUKKyRrZ7R 8qHtrlJp3doDVtVHDJ6vzrx68rV/gs5Nk8Jdj75+vlNZKDuVZWb55Uwlu9Tlqnkf1bNviK08 rM5cLuPbeJ3ZdmJM9aNfLYteNf/hmTTR7ZSR265FPrV7brsknnm3dmuY1pc5a+tTKwpzdvJr SgjsbFvk/NChv019/q1LmpsiJbTvcB2x/aW6+YSRT/rfNSc0l202Stg8ZUfIn5NLq35NYDP2 3zUhrJHnlJISS3FGoqEWc1FxIgBeqChJWgQAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFuplkeLIzCtJLcpLzFFi42LZdlhJTjfFxiHR4NZaRYuTT9awWTyYt43N 4uXPq2wWBx92slh8XfqM1eLT+mWsFqsXP2CxWHRjG5PF5V1z2Cy6r+9gs1h+/B+TRdfdG4wW S/+9ZXHg9bjc18vksXjPSyaPCYsOMHp8X9/B5vHx6S0Wj74tqxg9Pm+S82g/0M0UwBHFZZOS mpNZllqkb5fAlXH27VW2gltcFZPXd7E0MG7i6GLk5JAQMJF4+2YuUxcjF4eQwG5GiT331jNC JCQlTux8DmULS9xvOcIKUfSMUeLE5WPsIAk2AW2JaQ93gyVEBF4wSfzbv5kNJCEsoCixftkL FhCbRUBVYveUblYQm1fAUmLt6+ssELagxMmZT8BsZqBBT28+hbOXLXzNDLFZQeLn02VgvSIC ehKX/lxig6gRkZjd2cY8gVFgFpJRs5CMmoVk1CwkLQsYWVYxSqYWFOem5xYbFhjmpZbrFSfm Fpfmpesl5+duYgTHmJbmDsbtqz7oHWJk4mA8xCjBwawkwrvtjW2iEG9KYmVValF+fFFpTmrx IUZpDhYlcd4LXSfjhQTSE0tSs1NTC1KLYLJMHJxSDUzyNT/KQ+R+qi+wO7X/20ypvCqmv4fn bUv4v3X9e/YzvlVzu+onVth1B6yJsnM3bS6Vcvp25W3QkgyBRWt/m1ziMdJ3+b+qiVFw/jJu 1/khcSemTd3+54Le0z1CX/fXRTC+OOZx/L2F4uPr818/Zv2XonvVt/xvWIDezC1zUrrPuVx4 GCWyZIvVtWUee1bsv3H+n9/LE4Lt391N9t1IvXfg9ZYnarG2Z2cKz+w4ez+t+NgkjenXCydv Se1zfBgs8bs35s6Nd8HrTU9Muxhsdr87nFG3Nlnnb1bZuoDKYyvmHpCr3vL4mlDHtJNnI+/V Kbg0vZswrepRbYF3kNcGibU/lYQmbuvSO7foq3mJvGm1sxJLcUaioRZzUXEiAPSdduUgAwAA X-CMS-MailID: 20210914060836epcas2p2cf299639dba0abd11cdbe75534c9b9c9 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20210914060836epcas2p2cf299639dba0abd11cdbe75534c9b9c9 References: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > ufs_bsg was introduced nearly three years ago and it allocates its own > request queue. This is not related with ufs_bsg. I want to talk about a member under ufs_h= ba, cmd_queue. Very sorry for making you confused. > I faced a sytmpom with this and want to ask something about it. >=20 > That is, sometimes queue depth for ufs is limited to half of the its > maximum value even in a situation with many IO requests from filesystem. > It turned out that it only occurs when a query is being processed at the > same time. > Regarding my tracing, when the query process starts, users for the hctx > that represents a ufs host increase to two and with this, some pathes > calling 'hctx_may_queue' > function in blk-mq seems to throttle dispatches, technically with 16 > because the number of ufs slots (32 in my case) is dividend by two (users= ). >=20 > I found that it happened when a query for write booster is processed > because write booster only turns on in some conditions in my base that is > different from kernel mainline. But when an exceptional event or others > that could lead to a query occurs, it can happen even in mainline. >=20 > I think the throttling is a little bit excessive, so the question: is > there any way to assign queue depth per user on an asymmetric basis? >=20 > Thanks. > Kiwoong Kim