[Pvfs2-developers] acache timeout

[Phil Carns]

Dean Hildebrand wrote:
> Hi All,
> 
> I noticed my acache was never being used, and so I realized there is a 
> discrepancy between
> #define ACACHE_DEFAULT_TIMEOUT_MSECS 
> <ident?v=pvfs2-1.5.1-server;i=ACACHE_DEFAULT_TIMEOUT_MSECS> 5000
> and the default timeout passed in to pvfs2-client (which is '-a 5').
> 
> Is the intention when using the kernel module to reset the cache timeout 
> to 5msecs?  I'd prefer to stick with 5 seconds.

I have no idea why things are set up this way, but it has been like that 
for a while.  I helped rework the acache code at some point and left the 
same settings in place so that my patch didn't change semantics.

The pvfs2-client.c file defines its own defaults that it passes along to 
pvfs2-client-core unless you tell it otherwise:

#define DEFAULT_ACACHE_TIMEOUT_STR "5"

The easiest way to change it would be to edit your startup script for 
pvfs2-client to pass in --acache-timeout 5000 or -a 5000.  You can also 
change the parameter dynamically using 
/proc/sys/pvfs2/acache/timeout-msecs once pvfs2-client is running.

Bart Taylor posted some patches to the ncache that give you similar 
functionality for the name lookup cache (ie, command line and proc 
control of the timeout parameters) among other things, but I don't think 
it has been integrated in the tree yet.

-Phil