On 03 Jun 2013 16:27:06 +0200 Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
wrote:
> On Fri, Apr 19, 2013 at 06:56:00PM +0200, Bodo Stroesser wrote:
> >
> > We started the test of the -SP2 (and mainline) series on Tue, 9th, but had no
> > success.
> > We did _not_ find a problem with the patches, but under -SP2 our test scenario
> > has less than 40% of the throughput we saw under -SP1. With that low
> > performance, we had a 4 day run without any dropped RPC request. But we don't
> > know the error rate without the patches under these conditions. So we can't
> > give an o.k. for the patches yet.
> >
> > Currently we try to find the reason for the different behavior of SP1 and SP2
> >
>
> Hi,
>
> sorry for the delay. Meanwhile we found the reason for the small throughput
> with -SP2. The problem resulted from a change in our own software.
>
> Thus I could fix this and started a test on last Tuesday. I stopped the test
> today after 6 days without any lost RPC. Without the patches I saw the first
> dropped RPC after 3 hours. Thus, I think the patches for -SP2 are fine.
>
> @Neil: would patch 0006 of the -SP1 patchset be a good additional change for
> mainline?
>
> Bodo
Thanks for all the testing.
Bruce: where are you at with these? Are you holding one to some that I sent
previously, or should I resend them all?
Bodo: no, I don't think that patch is appropriate for mainline. It causes
sunrpc_cache_pipe_upcall to abort if ->expiry_time is zero. There is
certainly no point in doing an upcall in that case, but the code in mainline
is quite different to the code in -SP1 against which that patch made sense.
For mainline an equivalent optimisation which probably makes the interesting
case more obvious would be:
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index d01eb07..291cc47 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -262,7 +262,8 @@ int cache_check(struct cache_detail *detail,
if (rqstp == NULL) {
if (rv == -EAGAIN)
rv = -ENOENT;
- } else if (rv == -EAGAIN || age > refresh_age/2) {
+ } else if (rv == -EAGAIN ||
+ (refresh_age > 0 && age > refresh_age/2)) {
dprintk("RPC: Want update, refage=%ld, age=%ld\n",
refresh_age, age);
if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
i.e. trap that case in cache_check.
NeilBrown
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