Re: [PATCH] bio: skip atomic inc/dec of ->bi_remaining for non-chains

[Jan Kara <jack@suse.cz>]

On Mon 20-04-15 10:42:13, Jens Axboe wrote:
> On 04/20/2015 10:04 AM, Jan Kara wrote:
> >On Fri 17-04-15 08:59:33, Jens Axboe wrote:
> >>@@ -292,8 +292,8 @@ void bio_reset(struct bio *bio)
> >>  	__bio_free(bio);
> >>
> >>  	memset(bio, 0, BIO_RESET_BYTES);
> >>-	bio->bi_flags = flags|(1 << BIO_UPTODATE);
> >>-	atomic_set(&bio->bi_remaining, 1);
> >>+	bio->bi_flags = flags | 1 << BIO_UPTODATE;
> >   Although this is correct, I'd prefer to keep parenthesis around 1 <<
> >BIO_UPTODATE. Maybe I'm not a real C hacker but I had to lookup the
> >operator precedence of | vs << :).
> 
> Heh, I think we can safely say you are a real C hacker, lets just
> keep the parenthesis if that makes it easier to read/verify.
> 
> >Otherwise the patch looks good to me (but I'm not an expert in this area, I
> >just looked into the patch by accident because I thought it's another
> >respin of your direct IO patch ;).
> 
> It's a parallel effort, getting rid of the atomics where we can...
> Thanks for looking at it, can I add your reviewed-by tag with the
> parenthesis change?
  Yes, you can.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR