Re: The DM_BUFIO_HASH_BITS is defined as 20, any plan to make it flexible?
From: Mike Snitzer
Date: Wed Dec 03 2014 - 11:18:06 EST
On Wed, Dec 03 2014 at 9:19am -0500,
Joe Thornber <thornber@xxxxxxxxxx> wrote:
> On Tue, Dec 02, 2014 at 09:00:17AM -0500, Mike Snitzer wrote:
> > On Tue, Dec 02 2014 at 3:43am -0500,
> > zhangxiao <xiao.zhang@xxxxxxxxxxxxx> wrote:
> > > Hi Experts,
> > >
> > > See drivers/md/dm-bufio.c as below:
> > > 50 /*
> > > 51 * Buffer hash
> > > 52 */
> > > 53 #define DM_BUFIO_HASH_BITS 20
> > > 54 #define DM_BUFIO_HASH(block) \
> > > 55 ((((block) >> DM_BUFIO_HASH_BITS) ^ (block)) & \
> > > 56 ((1 << DM_BUFIO_HASH_BITS) - 1))
> > > "drivers/md/dm-bufio.c" 1854L, 45375C
> > >
> > > DM_BUFIO_HASH_BITS was defined as 20 and it maybe not fit for some
> > > use case with limited resources. Do we have any plan to make it more
> > > flexible? Like module parameter or something else?
> > No immediate plans.
> That hash table has been replaced with a red/black tree.
Ah yes, you'd think I'd have remembered that change. Thanks for keeping
me honest Joe!
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