From: "정요한(JOUNG YOHAN) Mobile SE" <yohan.joung@sk.com>
To: Bart Van Assche <bvanassche@acm.org>,
"Martin K . Petersen" <martin.petersen@oracle.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
"Avri Altman" <avri.altman@wdc.com>,
Bean Huo <beanhuo@micron.com>,
Stanley Chu <stanley.chu@mediatek.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
Matthias Brugger <matthias.bgg@gmail.com>
Subject: RE: [PATCH v3] scsi: ufs: Increase the maximum data buffer size
Date: Fri, 5 Aug 2022 01:54:06 +0000 [thread overview]
Message-ID: <f0464649f7e144c4a0536659201fc48b@sk.com> (raw)
In-Reply-To: <7a6499c6-4e98-072e-ce09-ddda7179b93e@acm.org>
> > In block layer, max_segment_size is obtained from get_max_segment_size.
> > seg_boundary_mask is set to PAGE_SIZE - 1 in the ufs driver.
> > The segment size is the PAGE size, and the max buffer size is segment
> > size * max segment count ( PAGE SIZE * 128 ) = 512 KiB in block layer
> > Right?
>
> Thanks for having reported this. I had overlooked that the UFS host
> controller driver sets the dma_boundary member of the host_template field.
> Is my understanding correct that UFS host controllers should support DMA
> segments that consist of multiple physical pages?
max value of data byte count is 256kb in PRDT.
256kb (data byte count) * 128 (max segments) = 32768kb
If physical pages are continuous, it seems that IO can be delivered up to 32mb.
performance checks are required, but we don't have to consider saturation.
because the device vendor can set opt_xfer_blocks .
Thanks,
yohan
>
> Thanks,
>
> Bart.
next prev parent reply other threads:[~2022-08-05 1:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-26 22:52 [PATCH v3] scsi: ufs: Increase the maximum data buffer size Bart Van Assche
2022-07-27 5:06 ` Avri Altman
2022-08-01 23:28 ` Martin K. Petersen
2022-08-02 23:40 ` 정요한(JOUNG YOHAN) Mobile SE
2022-08-03 16:23 ` Bart Van Assche
2022-08-04 1:50 ` 정요한(JOUNG YOHAN) Mobile SE
2022-08-04 17:48 ` Bart Van Assche
2022-08-05 1:54 ` 정요한(JOUNG YOHAN) Mobile SE [this message]
2022-09-02 14:52 ` Bean Huo
2022-09-06 18:04 ` Bart Van Assche
2022-09-15 10:56 ` Bean Huo
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