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util/oslib-posix: Introduce and use MemsetContext for touch_all_pages() 

Let's minimize the number of global variables to prepare for
os_mem_prealloc() getting called concurrently and make the code a bit
easier to read.

The only consumer that really needs a global variable is the sigbus
handler, which will require protection via a mutex in the future either way
as we cannot concurrently mess with the SIGBUS handler.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20211217134611.31172-4-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Hildenbrand 2021-12-17 14:46:06 +01:00 committed by Michael S. Tsirkin
parent a384bfa32e
commit dba506788b
1 changed files with 47 additions and 26 deletions
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73
util/oslib-posix.c
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@ -73,21 +73,30 @@
#define MAX_MEM_PREALLOC_THREAD_COUNT 16
struct MemsetThread;
typedef struct MemsetContext {
bool all_threads_created;
bool any_thread_failed;
struct MemsetThread *threads;
int num_threads;
} MemsetContext;
struct MemsetThread {
char *addr;
size_t numpages;
size_t hpagesize;
QemuThread pgthread;
sigjmp_buf env;
MemsetContext *context;
};
typedef struct MemsetThread MemsetThread;
static MemsetThread *memset_thread;
static int memset_num_threads;
/* used by sigbus_handler() */
static MemsetContext *sigbus_memset_context;
static QemuMutex page_mutex;
static QemuCond page_cond;
static bool threads_created_flag;
int qemu_get_thread_id(void)
{
@ -438,10 +447,13 @@ const char *qemu_get_exec_dir(void)
static void sigbus_handler(int signal)
{
int i;
if (memset_thread) {
for (i = 0; i < memset_num_threads; i++) {
if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
siglongjmp(memset_thread[i].env, 1);
if (sigbus_memset_context) {
for (i = 0; i < sigbus_memset_context->num_threads; i++) {
MemsetThread *thread = &sigbus_memset_context->threads[i];
if (qemu_thread_is_self(&thread->pgthread)) {
siglongjmp(thread->env, 1);
}
}
}
@ -459,7 +471,7 @@ static void *do_touch_pages(void *arg)
* clearing until all threads have been created.
*/
qemu_mutex_lock(&page_mutex);
while(!threads_created_flag){
while (!memset_args->context->all_threads_created) {
qemu_cond_wait(&page_cond, &page_mutex);
}
qemu_mutex_unlock(&page_mutex);
@ -502,7 +514,7 @@ static void *do_madv_populate_write_pages(void *arg)
/* See do_touch_pages(). */
qemu_mutex_lock(&page_mutex);
while (!threads_created_flag) {
while (!memset_args->context->all_threads_created) {
qemu_cond_wait(&page_cond, &page_mutex);
}
qemu_mutex_unlock(&page_mutex);
@ -529,6 +541,9 @@ static int touch_all_pages(char *area, size_t hpagesize, size_t numpages,
int smp_cpus, bool use_madv_populate_write)
{
static gsize initialized = 0;
MemsetContext context = {
.num_threads = get_memset_num_threads(smp_cpus),
};
size_t numpages_per_thread, leftover;
void *(*touch_fn)(void *);
int ret = 0, i = 0;
@ -546,35 +561,41 @@ static int touch_all_pages(char *area, size_t hpagesize, size_t numpages,
touch_fn = do_touch_pages;
}
threads_created_flag = false;
memset_num_threads = get_memset_num_threads(smp_cpus);
memset_thread = g_new0(MemsetThread, memset_num_threads);
numpages_per_thread = numpages / memset_num_threads;
leftover = numpages % memset_num_threads;
for (i = 0; i < memset_num_threads; i++) {
memset_thread[i].addr = addr;
memset_thread[i].numpages = numpages_per_thread + (i < leftover);
memset_thread[i].hpagesize = hpagesize;
qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
touch_fn, &memset_thread[i],
context.threads = g_new0(MemsetThread, context.num_threads);
numpages_per_thread = numpages / context.num_threads;
leftover = numpages % context.num_threads;
for (i = 0; i < context.num_threads; i++) {
context.threads[i].addr = addr;
context.threads[i].numpages = numpages_per_thread + (i < leftover);
context.threads[i].hpagesize = hpagesize;
context.threads[i].context = &context;
qemu_thread_create(&context.threads[i].pgthread, "touch_pages",
touch_fn, &context.threads[i],
QEMU_THREAD_JOINABLE);
addr += memset_thread[i].numpages * hpagesize;
addr += context.threads[i].numpages * hpagesize;
}
if (!use_madv_populate_write) {
sigbus_memset_context = &context;
}
qemu_mutex_lock(&page_mutex);
threads_created_flag = true;
context.all_threads_created = true;
qemu_cond_broadcast(&page_cond);
qemu_mutex_unlock(&page_mutex);
for (i = 0; i < memset_num_threads; i++) {
int tmp = (uintptr_t)qemu_thread_join(&memset_thread[i].pgthread);
for (i = 0; i < context.num_threads; i++) {
int tmp = (uintptr_t)qemu_thread_join(&context.threads[i].pgthread);
if (tmp) {
ret = tmp;
}
}
g_free(memset_thread);
memset_thread = NULL;
if (!use_madv_populate_write) {
sigbus_memset_context = NULL;
}
g_free(context.threads);
return ret;
}