On Monday March 5, [EMAIL PROTECTED] wrote:
> On Tue, 6 Mar 2007 13:15:20 +1100 NeilBrown <[EMAIL PROTECTED]> wrote:
>
> > Provide a module param "pool_mode" for sunrpc.ko which allows a
> > sysadmin to choose the mode for mapping NFS thread service pools
> > to CPUs. Values are:
> >
> > auto choose a mapping mode heuristically
> > global (default, same as the pre-2.6.19 code) a single global pool
> > percpu one pool per CPU
> > pernode one pool per NUMA node
> >
> > Note that since 2.6.19 the hardcoded behaviour has been "auto",
> > this patch makes the default "global".
> >
> > The pool mode can be changed after boot/modprobe using /sys, if the
> > NFS and lockd services have been shut down. A useful side effect of
> > this change is to fix a small memory leak when unloading the module.
>
> Mutter. Is this really suitable and needed for 2.6.21 at this stage in
> its life?
Something is definitely needed. Currently on a 4-way SMP machine,
nfsd might only use 1 CPU (depends a bit on irq routing I think).
If that patch is too big, maybe this one?
NeilBrown
--------------------------------
Avoid using nfsd process pools on SMP machines.
From: Neil Brown <[EMAIL PROTECTED]>
process-pools have real benefits for NUMA, but on SMP
machines they only work if network interface interrupts
go to all CPUs (via round-robin or multiple nics). This is
not always the case, so disable the pools in this case until
a better solution is developped.
Signed-off-by: Neil Brown <[EMAIL PROTECTED]>
### Diffstat output
./net/sunrpc/svc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff .prev/net/sunrpc/svc.c ./net/sunrpc/svc.c
--- .prev/net/sunrpc/svc.c 2007-03-06 16:07:19.000000000 +1100
+++ ./net/sunrpc/svc.c 2007-03-06 16:08:53.000000000 +1100
@@ -79,7 +79,11 @@ svc_pool_map_choose_mode(void)
* x86_64 kernel on Xeons. In this case we
* want to divide the pools on cpu boundaries.
*/
- return SVC_POOL_PERCPU;
+ /* actually, unless your IRQs round-robin nicely,
+ * this turns out to be really bad, so just
+ * go GLOBAL for now until a better fix can be developped
+ */
+ return SVC_POOL_GLOBAL;
}
/* default: one global pool */
-
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