Re: [dm-devel] The DM_BUFIO_HASH_BITS is defined as 20, any plan to make it flexible?

[zhangxiao]

On 2014å12æ03æ 22:19, Joe Thornber 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.
>
> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-for-3.19&id=4e420c452b11edf9d510c8180ac66f529e5b6206
Great Thanks!

Best Regards
Xiao
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