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Date:   Tue, 29 Mar 2022 07:40:45 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Yu Kuai <yukuai3@huawei.com>,
        andriy.shevchenko@linux.intel.com, john.garry@huawei.com,
        ming.lei@redhat.com, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [PATCH -next RFC 2/6] block: refactor to split bio thoroughly
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On Tue, Mar 29, 2022 at 08:35:29AM -0600, Jens Axboe wrote:
> > But more importantly why does your use case even have splits that get
> > submitted together?  Is this a case of Linus' stupidly low default
> > max_sectors when the hardware supports more, or is the hardware limited
> > to a low number of sectors per request?  Or do we hit another reason
> > for the split?
> 
> See the posted use case, it's running 512kb ios on a 128kb device.

That is an awfully low limit these days.  I'm really not sure we should
optimize the block layer for that.