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userfaultfd: selftests: refactor statistics
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Introduce uffd_stats structure for statistics of the self test, at the
same time refactor the code to always pass in the uffd_stats for either
read() or poll() typed fault handling threads instead of using two
different ways to return the statistic results.  No functional change.

With the new structure, it's very easy to introduce new statistics.

Signed-off-by: Peter Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Mike Rapoport <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Bobby Powers <[email protected]>
Cc: Brian Geffon <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Denis Plotnikov <[email protected]>
Cc: "Dr . David Alan Gilbert" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Martin Cracauer <[email protected]>
Cc: Marty McFadden <[email protected]>
Cc: Maya Gokhale <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Shaohua Li <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>
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@xzpeter @torvalds
xzpeter authored and torvalds committed Apr 7, 2020
1 parent 1481930 commit 5c8aed6
Showing 1 changed file with 49 additions and 27 deletions.
76 changes: 49 additions & 27 deletions tools/testing/selftests/vm/userfaultfd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,12 @@ static char *area_src, *area_src_alias, *area_dst, *area_dst_alias;
static char *zeropage;
pthread_attr_t attr;

/* Userfaultfd test statistics */
struct uffd_stats {
int cpu;
unsigned long missing_faults;
};

/* pthread_mutex_t starts at page offset 0 */
#define area_mutex(___area, ___nr) \
((pthread_mutex_t *) ((___area) + (___nr)*page_size))
Expand Down Expand Up @@ -125,6 +131,17 @@ static void usage(void)
exit(1);
}

static void uffd_stats_reset(struct uffd_stats *uffd_stats,
unsigned long n_cpus)
{
int i;

for (i = 0; i < n_cpus; i++) {
uffd_stats[i].cpu = i;
uffd_stats[i].missing_faults = 0;
}
}

static int anon_release_pages(char *rel_area)
{
int ret = 0;
Expand Down Expand Up @@ -467,8 +484,8 @@ static int uffd_read_msg(int ufd, struct uffd_msg *msg)
return 0;
}

/* Return 1 if page fault handled by us; otherwise 0 */
static int uffd_handle_page_fault(struct uffd_msg *msg)
static void uffd_handle_page_fault(struct uffd_msg *msg,
struct uffd_stats *stats)
{
unsigned long offset;

Expand All @@ -483,18 +500,19 @@ static int uffd_handle_page_fault(struct uffd_msg *msg)
offset = (char *)(unsigned long)msg->arg.pagefault.address - area_dst;
offset &= ~(page_size-1);

return copy_page(uffd, offset);
if (copy_page(uffd, offset))
stats->missing_faults++;
}

static void *uffd_poll_thread(void *arg)
{
unsigned long cpu = (unsigned long) arg;
struct uffd_stats *stats = (struct uffd_stats *)arg;
unsigned long cpu = stats->cpu;
struct pollfd pollfd[2];
struct uffd_msg msg;
struct uffdio_register uffd_reg;
int ret;
char tmp_chr;
unsigned long userfaults = 0;

pollfd[0].fd = uffd;
pollfd[0].events = POLLIN;
Expand Down Expand Up @@ -524,7 +542,7 @@ static void *uffd_poll_thread(void *arg)
msg.event), exit(1);
break;
case UFFD_EVENT_PAGEFAULT:
userfaults += uffd_handle_page_fault(&msg);
uffd_handle_page_fault(&msg, stats);
break;
case UFFD_EVENT_FORK:
close(uffd);
Expand All @@ -543,28 +561,27 @@ static void *uffd_poll_thread(void *arg)
break;
}
}
return (void *)userfaults;

return NULL;
}

pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;

static void *uffd_read_thread(void *arg)
{
unsigned long *this_cpu_userfaults;
struct uffd_stats *stats = (struct uffd_stats *)arg;
struct uffd_msg msg;

this_cpu_userfaults = (unsigned long *) arg;
*this_cpu_userfaults = 0;

pthread_mutex_unlock(&uffd_read_mutex);
/* from here cancellation is ok */

for (;;) {
if (uffd_read_msg(uffd, &msg))
continue;
(*this_cpu_userfaults) += uffd_handle_page_fault(&msg);
uffd_handle_page_fault(&msg, stats);
}
return (void *)NULL;

return NULL;
}

static void *background_thread(void *arg)
Expand All @@ -580,13 +597,12 @@ static void *background_thread(void *arg)
return NULL;
}

static int stress(unsigned long *userfaults)
static int stress(struct uffd_stats *uffd_stats)
{
unsigned long cpu;
pthread_t locking_threads[nr_cpus];
pthread_t uffd_threads[nr_cpus];
pthread_t background_threads[nr_cpus];
void **_userfaults = (void **) userfaults;

finished = 0;
for (cpu = 0; cpu < nr_cpus; cpu++) {
Expand All @@ -595,12 +611,13 @@ static int stress(unsigned long *userfaults)
return 1;
if (bounces & BOUNCE_POLL) {
if (pthread_create(&uffd_threads[cpu], &attr,
uffd_poll_thread, (void *)cpu))
uffd_poll_thread,
(void *)&uffd_stats[cpu]))
return 1;
} else {
if (pthread_create(&uffd_threads[cpu], &attr,
uffd_read_thread,
&_userfaults[cpu]))
(void *)&uffd_stats[cpu]))
return 1;
pthread_mutex_lock(&uffd_read_mutex);
}
Expand Down Expand Up @@ -637,7 +654,8 @@ static int stress(unsigned long *userfaults)
fprintf(stderr, "pipefd write error\n");
return 1;
}
if (pthread_join(uffd_threads[cpu], &_userfaults[cpu]))
if (pthread_join(uffd_threads[cpu],
(void *)&uffd_stats[cpu]))
return 1;
} else {
if (pthread_cancel(uffd_threads[cpu]))
Expand Down Expand Up @@ -908,11 +926,11 @@ static int userfaultfd_events_test(void)
{
struct uffdio_register uffdio_register;
unsigned long expected_ioctls;
unsigned long userfaults;
pthread_t uffd_mon;
int err, features;
pid_t pid;
char c;
struct uffd_stats stats = { 0 };

printf("testing events (fork, remap, remove): ");
fflush(stdout);
Expand All @@ -939,7 +957,7 @@ static int userfaultfd_events_test(void)
"unexpected missing ioctl for anon memory\n"),
exit(1);

if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &stats))
perror("uffd_poll_thread create"), exit(1);

pid = fork();
Expand All @@ -955,13 +973,13 @@ static int userfaultfd_events_test(void)

if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
perror("pipe write"), exit(1);
if (pthread_join(uffd_mon, (void **)&userfaults))
if (pthread_join(uffd_mon, NULL))
return 1;

close(uffd);
printf("userfaults: %ld\n", userfaults);
printf("userfaults: %ld\n", stats.missing_faults);

return userfaults != nr_pages;
return stats.missing_faults != nr_pages;
}

static int userfaultfd_sig_test(void)
Expand All @@ -973,6 +991,7 @@ static int userfaultfd_sig_test(void)
int err, features;
pid_t pid;
char c;
struct uffd_stats stats = { 0 };

printf("testing signal delivery: ");
fflush(stdout);
Expand Down Expand Up @@ -1004,7 +1023,7 @@ static int userfaultfd_sig_test(void)
if (uffd_test_ops->release_pages(area_dst))
return 1;

if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, &stats))
perror("uffd_poll_thread create"), exit(1);

pid = fork();
Expand All @@ -1030,6 +1049,7 @@ static int userfaultfd_sig_test(void)
close(uffd);
return userfaults != 0;
}

static int userfaultfd_stress(void)
{
void *area;
Expand All @@ -1038,7 +1058,7 @@ static int userfaultfd_stress(void)
struct uffdio_register uffdio_register;
unsigned long cpu;
int err;
unsigned long userfaults[nr_cpus];
struct uffd_stats uffd_stats[nr_cpus];

uffd_test_ops->allocate_area((void **)&area_src);
if (!area_src)
Expand Down Expand Up @@ -1167,8 +1187,10 @@ static int userfaultfd_stress(void)
if (uffd_test_ops->release_pages(area_dst))
return 1;

uffd_stats_reset(uffd_stats, nr_cpus);

/* bounce pass */
if (stress(userfaults))
if (stress(uffd_stats))
return 1;

/* unregister */
Expand Down Expand Up @@ -1211,7 +1233,7 @@ static int userfaultfd_stress(void)

printf("userfaults:");
for (cpu = 0; cpu < nr_cpus; cpu++)
printf(" %lu", userfaults[cpu]);
printf(" %lu", uffd_stats[cpu].missing_faults);
printf("\n");
}

Expand Down

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