Mailinglist Archive: opensuse-factory (458 mails)

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Re: [opensuse-factory] Btrfs under heavy write makes system sluggish-er than ext
On Tue, Nov 19, 2013 at 3:09 PM, Claudio Freire <klaussfreire@xxxxxxxxx> wrote:
On Tue, Nov 19, 2013 at 2:59 PM, Matthias G. Eckermann <mge@xxxxxxxx> wrote:
So, at least one conclusion can be drawn from this:

Under heaving writing, btrfs induces noticeably
higher read await times than ext4, resulting in the
considerably sluggish system I reported initially.
[...]
Yes, ext4 took longer (14 minutes longer). That could
be noise, the system wasn't totally idle (I was
browsing with firefox, painfully slowly, but inducing
some extra load). It does look though to be an I/O
scheduling issue more than a performance issue,
because restore times are comparable.

Well, so, in the end, btrfs was faster, but the system
less responsible to user interaction. Is that the right
summary?

Yep.

I think I managed to find a clue to a cause.

It seems heavy write activity on btrfs partitions induces higher
swappiness than the same activity in ext4. Not sure why. Decreasing
swappiness moderately improved responsiveness a great deal, so this
seems to be the right direction in finding a fix.
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