Re: [PATCH 3/5] nfsd: Only set PF_LESS_THROTTLE when really needed.

[Rik van Riel]

On 04/22/2014 10:40 PM, NeilBrown wrote:
> PF_LESS_THROTTLE has a very specific use case: to avoid deadlocks
> and live-locks while writing to the page cache in a loop-back
> NFS mount situation.
> 
> It therefore makes sense to *only* set PF_LESS_THROTTLE in this
> situation.
> We now know when a request came from the local-host so it could be a
> loop-back mount.  We already know when we are handling write requests,
> and when we are doing anything else.
> 
> So combine those two to allow nfsd to still be throttled (like any
> other process) in every situation except when it is known to be
> problematic.

The FUSE code has something similar, but on the "client"
side.

See BDI_CAP_STRICTLIMIT in mm/writeback.c

Would it make sense to use that flag on loopback-mounted
NFS filesystems?

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