Re: 2.4.25 - large inode_cache

[Jakob Oestergaard <jakob@unthought.net>]

On Thu, Feb 26, 2004 at 11:23:46AM -0300, Marcelo Tosatti wrote:
...
> > Will a heap of busy knfsd processes doing reads or writes exert
> > pressure?   Or is it only local userspace that can pressurize the VM (by
> > either anonymously backed memory or file I/O).
> 
> Any allocator will cause VM pressure.

And I suppose that a busy knfsd qualifies as an "allocator"   :)

...
> > Any enlightenment or suggestions are greatly appreciated :)
> 
> What you can try is to increase the VM tunable vm_vfs_scan_ratio. This is
> the proportion of VFS unused d/i caches that will try to be in one VM
> freeing pass. The default is 6. Try 4 or 3.
> 
> /proc/sys/vm/vm_vfs_scan_ratio

Done!  Set to 3 now - I will let the box run with this setting until
tomorrow, and report back how things look.

> You can also play with
> 
> /proc/sys/vm/vm_cache_scan_ratio (which is the percentage of cache which
> will be scanned in one go).

I'm leaving this one be for now (one variable at a time). But let's see
what tomorrow brings. 

Judging from the code, it seems that it's the vm_vfs_scan_ratio that
directly affects the icache/dcache and dquot - but I'm sure that there
are subtle interactions far beyond what I can possibly hope to
comprehend ;)

Thanks a lot for your suggestions Marcelo!

 / jakob