util/oslib-posix: Don't create too many threads with small memory or little pages
Let's limit the number of threads to something sane, especially that - We don't have more threads than the number of pages we have - We don't have threads that initialize small (< 64 MiB) memory Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> 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: <20211217134611.31172-5-david@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@ -40,6 +40,7 @@
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#include <libgen.h>
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#include <libgen.h>
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#include "qemu/cutils.h"
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#include "qemu/cutils.h"
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#include "qemu/compiler.h"
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#include "qemu/compiler.h"
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#include "qemu/units.h"
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#ifdef CONFIG_LINUX
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#ifdef CONFIG_LINUX
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#include <sys/syscall.h>
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#include <sys/syscall.h>
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@ -525,7 +526,8 @@ static void *do_madv_populate_write_pages(void *arg)
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return (void *)(uintptr_t)ret;
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return (void *)(uintptr_t)ret;
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}
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}
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static inline int get_memset_num_threads(int smp_cpus)
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static inline int get_memset_num_threads(size_t hpagesize, size_t numpages,
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int smp_cpus)
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{
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{
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long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
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long host_procs = sysconf(_SC_NPROCESSORS_ONLN);
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int ret = 1;
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int ret = 1;
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@ -533,6 +535,12 @@ static inline int get_memset_num_threads(int smp_cpus)
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if (host_procs > 0) {
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if (host_procs > 0) {
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ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
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ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus);
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}
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}
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/* Especially with gigantic pages, don't create more threads than pages. */
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ret = MIN(ret, numpages);
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/* Don't start threads to prealloc comparatively little memory. */
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ret = MIN(ret, MAX(1, hpagesize * numpages / (64 * MiB)));
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/* In case sysconf() fails, we fall back to single threaded */
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/* In case sysconf() fails, we fall back to single threaded */
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return ret;
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return ret;
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}
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}
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@ -542,7 +550,7 @@ static int touch_all_pages(char *area, size_t hpagesize, size_t numpages,
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{
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{
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static gsize initialized = 0;
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static gsize initialized = 0;
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MemsetContext context = {
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MemsetContext context = {
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.num_threads = get_memset_num_threads(smp_cpus),
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.num_threads = get_memset_num_threads(hpagesize, numpages, smp_cpus),
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};
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};
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size_t numpages_per_thread, leftover;
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size_t numpages_per_thread, leftover;
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void *(*touch_fn)(void *);
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void *(*touch_fn)(void *);
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