From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>,
martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: please revert the UFS HPB support
Date: Thu, 21 Oct 2021 17:17:28 +0200 [thread overview]
Message-ID: <20211021151728.GA31600@lst.de> (raw)
In-Reply-To: <20211021151520.GA31407@lst.de>
On Thu, Oct 21, 2021 at 05:15:20PM +0200, Christoph Hellwig wrote:
> > > I just noticed the UFS HPB support landed in 5.15, and just as
> > > before it is completely broken by allocating another request on
> > > the same device and then reinserting it in the queue. It is bad
> > > enough that we have to live with blk_insert_cloned_request for
> > > dm-mpath, but this is too big of an API abuse to make it into
> > > a release. We need to drop this code ASAP, and I can prepare
> > > a patch for that.
> >
> > That sounds awful, do you have a link to the offending commit(s)?
>
> I'll need to look for it, busy in calls right now, but just grep for
> blk_insert_cloned_request.
Might as well finish the git blame:
commit 41d8a9333cc96f5ad4dd7a52786585338257d9f1
Author: Daejun Park <daejun7.park@samsung.com>
Date: Mon Jul 12 18:00:25 2021 +0900
scsi: ufs: ufshpb: Add HPB 2.0 support
Version 2.0 of HBP supports reads of varying sizes from 4KB to 1MB.
A read operation <= 32KB is supported as single HPB read. A read between
36KB and 1MB is supported by a combination of write buffer command and HPB
read command to deliver more PPN. The write buffer commands may not be
issued immediately due to busy tags. To use HPB read more aggressively, the
driver can requeue the write buffer command. The requeue threshold is
implemented as timeout and can be modified with requeue_timeout_ms entry in
sysfs.
next prev parent reply other threads:[~2021-10-21 15:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 14:42 please revert the UFS HPB support Christoph Hellwig
2021-10-21 15:13 ` Jens Axboe
2021-10-21 15:15 ` Christoph Hellwig
2021-10-21 15:17 ` Christoph Hellwig [this message]
2021-10-21 16:22 ` Bart Van Assche
2021-10-23 15:43 ` James Bottomley
[not found] ` <CGME20211023154316epcas2p208f95cf1e4a87a4b61d2daf1a2b3c725@epcms2p3>
2021-10-25 5:16 ` Daejun Park
2021-10-25 7:07 ` Christoph Hellwig
2021-10-25 11:39 ` James Bottomley
2021-10-23 1:54 ` Martin K. Petersen
2021-10-23 4:40 ` Christoph Hellwig
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