Gilles Carry wrote:
> Before doing any disk I/O, put back thread to SCHED_OTHER/prio 0.
>
I guess I still don't fully understand why this is an issue. A
real-time task will be put to sleep waiting on I/O to complete just like
any other task. Perhaps this is just ignorance on my part, while you
certainly shouldn't expect low latency from an rt thread that is doing
I/O, I don't see why it shouldn't do I/O at all, even if latency is
known not to be an issue. I don't really object to the patch, but I
would like to understand why it is needed.
--
Darren
> Signed-off-by: Gilles Carry <[EMAIL PROTECTED]>
> ---
> testcases/realtime/func/matrix_mult/matrix_mult.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/testcases/realtime/func/matrix_mult/matrix_mult.c
> b/testcases/realtime/func/matrix_mult/matrix_mult.c
> index aef626a..0d4eb7a 100644
> --- a/testcases/realtime/func/matrix_mult/matrix_mult.c
> +++ b/testcases/realtime/func/matrix_mult/matrix_mult.c
> @@ -279,12 +279,16 @@ void main_thread(void)
> /* run matrix mult operation sequentially */
> curdat = &sdat;
> printf("\nRunning sequential operations\n");
> + set_priority(PRIO);
> start = rt_gettime();
> for (i = 0; i < iterations; i++)
> matrix_mult_record(MATRIX_SIZE, i);
> end = rt_gettime();
> delta = (long)((end - start)/NS_PER_US);
>
> + /* Go back to normal prio before doing any disk activity */
> + set_priority_other(0);
> +
> savg = delta/iterations; /* don't use the stats record, use the total
> time recorded */
> smin = stats_min(&sdat);
> smax = stats_max(&sdat);
> @@ -305,6 +309,7 @@ void main_thread(void)
> fprintf(stderr, "Warning: could not save sequential mults
> stats\n");
> }
>
> + set_priority(PRIO);
> /* Create numcpus-1 concurrent threads */
> for (j = 0; j < (numcpus-1); j++) {
> tids[j] = create_fifo_thread(concurrent_thread, (void
> *)(intptr_t)j, PRIO);
> @@ -335,6 +340,9 @@ void main_thread(void)
> pthread_mutex_unlock(&t->mutex);
> }
>
> + /* Go back to normal prio before doing any disk activity */
> + set_priority_other(0);
> +
> cavg = delta/iterations; /* don't use the stats record, use the total
> time recorded */
> cmin = stats_min(&cdat);
> cmax = stats_max(&cdat);
> @@ -408,7 +416,6 @@ int main(int argc, char *argv[])
> printf("jvmsim disabled\n");
> }
>
> - set_priority(PRIO);
> main_thread();
>
> join_threads();
--
Darren Hart
IBM Linux Technology Center
Real-Time Linux Team
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