Re: [RFC] md/raid5: optimize RAID5 performance.

Song Liu
2023-11-27T23:21:59Z

On Mon, Nov 27, 2023 at 4:21 AM Paul E Luse <paul.e.luse@linux.intel.com> wrote:
>
> On Sun, 26 Nov 2023 22:44:45 -0800
> Christoph Hellwig <hch@infradead.org> wrote:
>
> > Hi Shushu,
> >
> > the work certainly looks interesting!
> >
> > However:
> >
> > > Optimized by using fine-grained locks, customized data structures,
> > > and scattered address space. Achieves significant improvements in
> > > both throughput and latency.
> >
> > this is a lot of work for a single Linux patch, we usually do that
> > work pice by pice instead of complete rewrite, and for such
> > signigicant changes the commit logs also tend to be a bit extensive.
> >
> > I'm also not quite sure what scattered address spaces are - I bet
> > reading the paper (I plan to get to that) would explain it, but it
> > also helps to explain the idea in the commit message.
> >
> > That's my high level nitpicking for now, I'll try to read the paper
> > and the patch in detail and come back later.
> >
> >
>
> For sure the paper provides a lot more context. Is there more
> performance data avialble, like a general sweep of various IO sizes,
> patterns and queue depths? ALso, what kind of data integrity testing
> has been done?

Echo comments from Christoph and Paul. Also, please run
./scripts/checkpatch.pl on the patches before sending. It will catch a lot
of issues. Please also clean up the code before sending the patches.
Something like the following should not be included in the patch.

+ // new_bmclocks = kcalloc(num_bmclocks, sizeof(*new_bmclocks),
GFP_KERNEL);

Thanks,
Song