[gentoo-user] Re: Firefox occasionally stalls

[Kai Krakow]

Am Wed, 22 Mar 2017 15:12:36 +0000
schrieb Peter Humphrey <peter@××××××××××××.uk>:

> On Tuesday 21 Mar 2017 22:50:04 Kai Krakow wrote:
>
> ---<8
>
> > I'm combining this with bcache. That's a cache between kernel and
> > filesystem that you put on SSD. Apparently, it requires
> > repartitioning to map your filesystem through bcache (it has to add
> > a protective superblock in front of your FS). So, a small SSD +
> > bcache can make your complete 500GB spinning rust act mostly like
> > SSD perfomance-wise.
> >
> > I think there's a script that can move your FS 8 kB forward on HDD
> > to add that bcache superblock. But I wouldn't try that without
> > backup and some spare time. But it is a performance wonder.
> >
> > Using 3x 1TB btrfs RAID + 500GB bcache here. The system feels like
> > an SSD system but I don't have to decide what to put on a small SSD
> > and what to put on big slow storage. Is just automagic. ;-)
>
> You have me thinking now. I have a couple of spare 1TB SSDs here, and
> my workstation is a 12-core i7 running on a 256GB NVMe drive with 32
> GB RAM.
>
> Maybe I should put the SSDs into a RAID-1 to contain the system (the
> same as they were in the old, now defunct box), then use the NVMe for
> bcache. What do you think of that idea? I'm not desperately short of
> space, but I've none spare either.

I'm not sure if bcache can use NVMe at their full potential... Maybe
head over to the bcache list and ask there. I think it faces some write
serialization issues while NVMe should better work with multi-queue
scheduler.

If you're going to use mdraid, maybe better look into mdcache.

But your results would be interesting. :-)


-- 
Regards,
Kai

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