On Wed, 2008-10-22 at 13:51 +0200, Gilles Carry wrote:
> From: gilles.carry <[EMAIL PROTECTED]>
>
> Syscall sched_setaffinity fails if choosen cpu is not online.
> In set_affinity, thread_id value is used as cpuid when calling
> sched_setaffinity. This fails when disabling cpus because threads ids
> and online cpu ids don't necessarly match.
>
> This patch simply increments cpuid (max. 8192) until it finds an online cpu.
> This guaranties that no more than one thread is assigned to one cpu.
> If set_affinity is called more times than there are online cpus
> then matrix_mult.c fails.
>
> Signed-off-by: Gilles Carry <[EMAIL PROTECTED]>
Looks like you'll be shaving your head, Gilles :) Attach a picture
please!
> ---
> testcases/realtime/func/matrix_mult/matrix_mult.c | 58 ++++++++++++++------
> 1 files changed, 40 insertions(+), 18 deletions(-)
>
> diff --git a/testcases/realtime/func/matrix_mult/matrix_mult.c
> b/testcases/realtime/func/matrix_mult/matrix_mult.c
> index 21fded8..a551687 100644
> --- a/testcases/realtime/func/matrix_mult/matrix_mult.c
> +++ b/testcases/realtime/func/matrix_mult/matrix_mult.c
> @@ -44,6 +44,7 @@
> #include <libjvmsim.h>
> #include <libstats.h>
>
> +#define MAX_CPUS 8192
> #define PRIO 43
> #define MATRIX_SIZE 100
> #define DEF_OPS 8 /* the higher the number, the
> more CPU intensive */
> @@ -66,15 +67,13 @@ static float criteria;
> static int *mult_index;
> static int *tids;
> static int *flags;
> +static int online_cpu_id = -1;
>
> stats_container_t sdat, cdat, *curdat;
> stats_container_t shist, chist;
> static pthread_barrier_t mult_start;
> +static pthread_mutex_t mutex_cpu;
>
> -int gettid(void)
> -{
> - return syscall(__NR_gettid);
> -}
>
> void usage(void)
> {
> @@ -148,28 +147,42 @@ void matrix_mult_record(int m_size, int index)
> curdat->records[index].y = delta;
> }
>
> -int set_affinity(int cpuid)
> +int set_affinity(void)
> {
> - int tid = gettid();
> cpu_set_t mask;
> -
> - CPU_ZERO(&mask);
> - CPU_SET(cpuid, &mask);
> -
> - if (sched_setaffinity(0, sizeof(mask), &mask) < 0) {
> - printf("Thread %d: Can't set affinity: %s\n", tid,
> strerror(errno));
You'll want to use fprintf(stderr,...) here ??
> - exit(1);
> - }
> -
> - return 0;
> + int cpuid;
> +
> + pthread_mutex_lock(&mutex_cpu);
> + do {
> + ++online_cpu_id;
> + CPU_ZERO(&mask);
> + CPU_SET(online_cpu_id, &mask);
> +
> + if (!sched_setaffinity(0, sizeof(mask), &mask)) {
> + cpuid = online_cpu_id; /* Save this value before
> unlocking mutex */
> + pthread_mutex_unlock(&mutex_cpu);
> + return cpuid;
> + }
> + } while (online_cpu_id < MAX_CPUS);
> + pthread_mutex_unlock(&mutex_cpu);
> + return -1;
> }
>
> void *concurrent_thread(void *thread)
> {
> struct thread *t = (struct thread *)thread;
> int thread_id = (intptr_t)t->arg;
> + int cpuid;
> +
> + cpuid = set_affinity();
> + if (cpuid == -1) {
> + printf("Thread %d: Can't set affinity.\n", thread_id);
Ditto.
> + exit(1);
> + } else {
> + if (_dbg_lvl)
> + printf("Thread %d: Affinity set to cpu%d\n", thread_id,
> cpuid);
> + }
First, I do not think _dbg_lvl was not meant for use outside of
librttest. You should be using the debug() macro. For example,
debug(DBG_INFO, "RIP: Here lies the quick brown fox. He was not quick enough.")
Second, why are you even using it? As it stands, tt doesn't seem at all
consistent with how reporting is done by this test case as a whole. If
you want to introduce the debug() macro to the matrix_mult testcase, you
might consider introducing it as a separate patch that takes the whole
testcase into consideration?
>
> - set_affinity(thread_id);
> pthread_barrier_wait(&mult_start);
> while (flags[thread_id] != THREAD_DONE) {
> pthread_mutex_lock(&t->mutex);
> @@ -219,6 +232,7 @@ void main_thread(void)
> nsec_t start, end;
> long smin = 0, smax = 0, cmin = 0, cmax = 0, delta = 0;
> float savg, cavg;
> + int cpuid;
>
> if ( stats_container_init(&sdat, ITERATIONS) ||
> stats_container_init(&shist, HIST_BUCKETS) ||
> @@ -251,7 +265,15 @@ void main_thread(void)
> }
> memset(flags, 0, numcpus);
>
> - set_affinity(numcpus-1);
> + cpuid = set_affinity();
> + if (cpuid == -1) {
> + printf("Main thread: Can't set affinity.\n");
Same as above.
> + exit(1);
> + } else {
> + if (_dbg_lvl)
> + printf("Main thread: Affinity set to cpu%d\n", cpuid);
> + }
> +
Same as above.
>
> /* run matrix mult operation sequentially */
> curdat = &sdat;
--
-tim
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