Re: [PATCH 1/7] ѕd: split sd_setup_discard_cmnd

2017-03-30 Thread h...@lst.de 
On Tue, Mar 28, 2017 at 08:05:09AM -0600, ax...@kernel.dk wrote:
> > Although I know this is an issue in the existing code and not something
> > introduced by you: please consider using logical_to_sectors() instead of
> > open-coding this function. Otherwise this patch looks fine to me.
> 
> The downside of doing that is that we still call ilog2() twice, which
> sucks. Would be faster to cache ilog2(sector_size) and use that in the
> shift calculation.

I suspect that gcc is smart enough to optimize it away.  That beeing said
while this looks like a nice cleanup this patch is just supposed to move
code, so I'd rather not add the change here and leave it for a separate
submission.

Re: [PATCH 1/7] ѕd: split sd_setup_discard_cmnd

2017-03-28 Thread ax...@kernel.dk 
On Mon, Mar 27 2017, Bart Van Assche wrote:
> On Mon, 2017-03-20 at 16:43 -0400, Christoph Hellwig wrote:
> > +   u64 sector = blk_rq_pos(rq) >> (ilog2(sdp->sector_size) - 9);
> > +   u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
> 
> Although I know this is an issue in the existing code and not something
> introduced by you: please consider using logical_to_sectors() instead of
> open-coding this function. Otherwise this patch looks fine to me.

The downside of doing that is that we still call ilog2() twice, which
sucks. Would be faster to cache ilog2(sector_size) and use that in the
shift calculation.

-- 
Jens Axboe

Re: [PATCH 1/7] ѕd: split sd_setup_discard_cmnd

2017-03-27 Thread Bart Van Assche 
On Mon, 2017-03-20 at 16:43 -0400, Christoph Hellwig wrote:
> + u64 sector = blk_rq_pos(rq) >> (ilog2(sdp->sector_size) - 9);
> + u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);

Although I know this is an issue in the existing code and not something
introduced by you: please consider using logical_to_sectors() instead of
open-coding this function. Otherwise this patch looks fine to me.

Thanks,

Bart.