From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: [PATCH 1/2] raid5-cache: use a bio_set Date: Wed, 2 Dec 2015 21:01:05 -0800 Message-ID: <20151203050056.GC3111265@devbig084.prn1.facebook.com> References: <1449072638-15409-1-git-send-email-hch@lst.de> <1449072638-15409-2-git-send-email-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <1449072638-15409-2-git-send-email-hch@lst.de> Sender: linux-raid-owner@vger.kernel.org To: Christoph Hellwig Cc: neilb@suse.com, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, Dec 02, 2015 at 05:10:37PM +0100, Christoph Hellwig wrote: > This allows us to make guaranteed forward progress. > > Signed-off-by: Christoph Hellwig > --- > drivers/md/raid5-cache.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c > index 668e973..ef59564 100644 > --- a/drivers/md/raid5-cache.c > +++ b/drivers/md/raid5-cache.c > @@ -34,6 +34,12 @@ > #define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */ > #define RECLAIM_MAX_FREE_SPACE_SHIFT (2) > > +/* > + * We only need 2 bios per I/O unit to make progress, but ensure we > + * have a few more available to not get too tight. > + */ > +#define R5L_POOL_SIZE 1024 Looks reasonable, the recent arbitrary size bio makes things simpler. I think we don't need to be that conservative. One metadata page can hold at most (PAGE_SIZE - sizeof(struct r5l_meta_block)) / sizeof(struct r5l_payload_data_parity) pages. Thanks, Shaohua