Hi Matthew,
On Sat, Mar 11, 2017 at 06:56:40AM -0800, Matthew Wilcox wrote:
> On Mon, Feb 06, 2017 at 12:16:44AM +0900, Minchan Kim wrote:
> > +static inline void zram_fill_page(char *ptr, unsigned long len,
> > + unsigned long value)
> > +{
> > + int i;
> > + unsigned long *page = (unsigned long *)ptr;
> > +
> > + WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
> > +
> > + if (likely(value == 0)) {
> > + memset(ptr, 0, len);
> > + } else {
> > + for (i = 0; i < len / sizeof(*page); i++)
> > + page[i] = value;
> > + }
> > +}
>
> I've hacked up memset32/memset64 for both ARM and x86 here:
>
> http://git.infradead.org/users/willy/linux-dax.git/shortlog/refs/heads/memfill
Thanks for the patch.
>
> Can you do some performance testing and see if it makes a difference?
I tested that zram is *full* with non-zero 100M dedupable data(i.e.,
it's a ideal case) on x86. With this, I see 7% enhancement.
perf stat -r 10 dd if=/dev/zram0 of=/dev/null
vanilla: 0.232050465 seconds time elapsed ( +- 0.51% )
memset_l: 0.217219387 seconds time elapsed ( +- 0.07% )
I doubt it makes such benefit in read workload which a small percent
non-zero dedup data(e.g., under 3%) but it makes code simple/perform
win.
Thanks.
>
> At this point, I'd probably ask for the first 5 patches in that git
> branch to be included, and leave out memfill and the shoddy testsuite.
>
> I haven't actually tested either asm implementation ... only the
> C fallback.
