Hi Bart,
On Mon, Mar 23, 2020 at 08:09:27PM -0700, Bart Van Assche wrote:
> On 2020-03-23 04:29, Daniel Wagner wrote:
> > On Fri, Mar 20, 2020 at 03:24:13PM -0700, Bart Van Assche wrote:
> >> +test() {
> >> + local i sq=/sys/kernel/config/nullb/nullb0/submit_queues
> >> +
> >> + : "${TIMEOUT:=30}"
> >> + if ! _init_null_blk nr_devices=0 queue_mode=2 "init_hctx=$(nproc),100,0,0"; then
>From the kernel code:
/* "<interval>,<probability>,<space>,<times>" */
Don't you need to set the times attribute to -1 in order to inject the
everytime the interval is reached? If I understood it correctly,
with times=0 no failure is injected.
BTW, I've had to change it to init_hctx=$(($(nproc)+1)) to pass
the initial __configure_null_blk call before the first fail hits.
> > Doesn't make the $(nproc) the test subtil depending on the execution
> > environment?
> The value $(nproc) has been chosen on purpose. The following code from
> the test script:
>
> + echo 1 >$sq
> + nproc >$sq
>
> triggers (nproc + 1) calls to null_init_hctx().So injecting a failure
> after (nproc) null_init_hctx() calls triggers the following pattern:
> * The first blk_mq_realloc_hw_ctxs() call fails after (nproc - 1)
> null_init_hctx() calls.
> * The second blk_mq_realloc_hw_ctxs() call fails after (nproc - 2)
> null_init_hctx() calls.
> ...
> * The (nproc) th blk_mq_realloc_hw_ctxs() call fails after one
> null_init_hctx() call.
> * The (nproc + 1) th blk_mq_realloc_hw_ctxs() call succeeds.
>
> I'm not sure to trigger this behavior without using the $(nproc) value?
Okay, I get the idea how you want to test.
Is the dependency on nproc because null_blk expects submit_queue <= online
cpus?
Though why the 100?
for ((i=0;i<100;i++)); do
echo 1 >$sq
nproc >$sq
done
And shouldn't be there a test for error?
Thanks,
Daniel
