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SubjectRe: [PATCH 2/3] rhashtable-test: retry insert operations in threads
On Fri, Aug 28, 2015 at 01:09:29PM +0200, Thomas Graf wrote:
> On 08/28/15 at 12:28pm, Phil Sutter wrote:
> > After adding cond_resched() calls to threadfunc(), a surprisingly high
> > rate of insert failures occurred probably due to table resizes getting a
> > better chance to run in background. To not soften up the remaining
> > tests, retry inserts until they either succeed or fail permanently.
> >
> > Signed-off-by: Phil Sutter <phil@nwl.cc>
> > ---
> > lib/test_rhashtable.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
> > index 63654e3..093cf84 100644
> > --- a/lib/test_rhashtable.c
> > +++ b/lib/test_rhashtable.c
> > @@ -244,7 +244,7 @@ static int thread_lookup_test(struct thread_data *tdata)
> >
> > static int threadfunc(void *data)
> > {
> > - int i, step, err = 0, insert_fails = 0;
> > + int i, step, err = 0, retries = 0;
> > struct thread_data *tdata = data;
> >
> > up(&prestart_sem);
> > @@ -253,21 +253,22 @@ static int threadfunc(void *data)
> >
> > for (i = 0; i < entries; i++) {
> > tdata->objs[i].value = (tdata->id << 16) | i;
> > +insert_retry:
> > cond_resched();
> > err = rhashtable_insert_fast(&ht, &tdata->objs[i].node,
> > test_rht_params);
> > if (err == -ENOMEM || err == -EBUSY) {
> > - tdata->objs[i].value = TEST_INSERT_FAIL;
> > - insert_fails++;
> > + retries++;
> > + goto insert_retry;
>
> Is it safe to retry indefinitely on ENOMEM? Retrying on EBUSY is
> definitely an improvement and we should do the same in the non
> threaded test as well.

Oh yes, that is definitely a bug. I will respin and add the same for the
normal test, too.

Thanks, Phil


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