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From:   Changheun Lee <nanich.lee@samsung.com>
To:     damien.lemoal@wdc.com
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Subject: Re: [PATCH v11 3/3] scsi: set max_bio_bytes with queue max sectors
Date:   Thu,  3 Jun 2021 17:32:36 +0900
Message-Id: <20210603083236.18161-1-nanich.lee@samsung.com>
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> On 2021/06/02 21:29, Changheun Lee wrote:
> > Set max_bio_bytes same with queue max sectors. It will lead to fast bio
> > submit when bio size is over than queue max sectors. And it might be helpful
> > to align submit bio size in some case.
> > 
> > Signed-off-by: Changheun Lee <nanich.lee@samsung.com>
> > ---
> >  drivers/scsi/scsi_lib.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index 532304d42f00..f6269268b0e0 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -1837,6 +1837,8 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
> >  	blk_queue_virt_boundary(q, shost->virt_boundary_mask);
> >  	dma_set_max_seg_size(dev, queue_max_segment_size(q));
> >  
> > +	blk_queue_max_bio_bytes(q, queue_max_sectors(q));
> 
> Doing this unconditionally for all scsi block devices is probably not a good
> idea. Cannot this be moved to the LLD handling the devices that actually need it ?

OK, I'll try to check more nice location in LLD.

> 
> > +
> >  	/*
> >  	 * Set a reasonable default alignment:  The larger of 32-byte (dword),
> >  	 * which is a common minimum for HBAs, and the minimum DMA alignment,
> > 
> 
> 
> -- 
> Damien Le Moal
> Western Digital Research

Thank you,
Changheun Lee