Re: [PATCH 1/2] zram: free meta out of init_lock

Minchan Kim
2015-01-28T05:35:50Z

On Wed, Jan 28, 2015 at 01:58:55PM +0900, Minchan Kim wrote:
> On Wed, Jan 28, 2015 at 01:50:28PM +0900, Sergey Senozhatsky wrote:
> > On (01/28/15 13:07), Sergey Senozhatsky wrote:
> > > On (01/28/15 12:53), Sergey Senozhatsky wrote:
> > > > > So, I want to go with srcu. Do you agree? or another suggestion?
> > > >
> > > > yes, I think we need to take a second look on srcu approach.
> > > >
> > >
> > > ... or we can ask lockdep to stop false alarming us and leave it as is.
> > > I wouldn't say that ->init_lock is so hard to understand.
> > > just as an option.
> > >
> >
> > so... returning back to barriers performance implications.
> >
> > x86_64, lzo, 4 comp streams, 2G zram, ext4, mount -o rw,relatime,data=ordered
> >
> > ./iozone -t 3 -R -r 16K -s 60M -I +Z
> >
> > test base srcu
> > " Initial write " 1299639.75 1277621.03
> > " Rewrite " 2139387.50 2004663.94
> > " Read " 6193415.00 5091000.00
> > " Re-read " 6199050.38 4814297.88
> > " Reverse Read " 4693868.88 4367201.75
> > " Stride read " 4470633.75 4247550.00
> > " Random read " 5115339.50 4517352.75
> > " Mixed workload " 4340747.06 3880517.31
> > " Random write " 1982369.75 1892456.25
> > " Pwrite " 1352550.22 1248667.78
> > " Pread " 2853150.06 2445154.41
> > " Fwrite " 2367397.81 2262384.56
> > " Fread " 8100746.50 7578071.75
> >
> > not good.
> >
>
> Oops, I never thought it could make mesurable performance.
> I will investigate it.
>
> Thanks a lot, Sergey!

Sergey, the data is consistent for repeated work?

I tested it with dd on /dev/zram0 without any FS on my KVM
and I cannot see any measureable performance gap.
Hmm, I will try it on real machine.

--
Kind regards,
Minchan Kim