Re: [PATCHSET v3][RFC] Make background writeback not suck

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Mar 31, 2016 at 10:09:56PM +0000, Holger Hoffstätte wrote:
> 
> Hi,
> 
> Jens mentioned on Twitter I should post my experience here as well,
> so here we go.
> 
> I've backported this series (incl. updates) to stable-4.4.x - not too
> difficult, minus the NVM part which I don't need anyway - and have been
> running it for the past few days without any problem whatsoever, with
> GREAT success.
> 
> My use case is primarily larger amounts of stuff (transcoded movies,
> finished downloads, built Gentoo packages) that gets copied from tmpfs
> to SSD (or disk) and every time that happens, the system noticeably
> strangles readers (desktop, interactive shell). It does not really matter
> how I tune writeback via the write_expire/dirty_bytes knobs or the
> scheduler (and yes, I understand how they work); lowering the writeback
> limits helped a bit but the system is still overwhelmed. Jacking up
> deadline's writes_starved to unreasonable levels helps a bit, but in turn
> makes all writes suffer. Anything else - even tried BFQ for a while,
> which has its own unrelated problems - didn't really help either.

Can you go back to your original kernel, and lower nr_requests to 8?

Essentially all I see the block throttle doing is keeping the
request queue depth to somewhere between 8-12 requests, rather than
letting it blow out to near nr_requests (around 105-115), so it
would be interesting to note whether the block throttling has any
noticable difference in behaviour when compared to just having a
very shallow request queue....

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux