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Subject: Re: Slow I/O on USB media after commit
 f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6
From:   Andrea Vai <andrea.vai@unipv.it>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Damien Le Moal <Damien.LeMoal@wdc.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        Jens Axboe <axboe@kernel.dk>,
        Johannes Thumshirn <jthumshirn@suse.de>,
        USB list <linux-usb@vger.kernel.org>,
        SCSI development list <linux-scsi@vger.kernel.org>,
        Himanshu Madhani <himanshu.madhani@cavium.com>,
        Hannes Reinecke <hare@suse.com>,
        Omar Sandoval <osandov@fb.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        Hans Holmberg <Hans.Holmberg@wdc.com>,
        Kernel development list <linux-kernel@vger.kernel.org>
Date:   Mon, 25 Nov 2019 19:51:33 +0100
In-Reply-To: <20191125151535.GA8044@ming.t460p>
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Il giorno lun, 25/11/2019 alle 23.15 +0800, Ming Lei ha scritto:
> On Mon, Nov 25, 2019 at 03:58:34PM +0100, Andrea Vai wrote:
> 
> [...]
> 
> > What to try next?
> 
> 1) cat /sys/kernel/debug/block/$DISK/hctx0/flags
result:

alloc_policy=FIFO SHOULD_MERGE|2

> 
> 
> 2) echo 128 > /sys/block/$DISK/queue/nr_requests and run your copy
> 1GB
> test again.

done, and still fails. What to try next?

Thanks,
Andrea