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author | David Hildenbrand <david@redhat.com> | 2021-12-17 14:46:07 +0100 |
---|---|---|
committer | Michael S. Tsirkin <mst@redhat.com> | 2022-01-07 05:19:55 -0500 |
commit | 89aec6411c429adb662c53c94a986a5397961a7f (patch) | |
tree | 430c01ebb424f95438075cada44940c1dc5c609f /util/oslib-posix.c | |
parent | dba506788b0f84a45c69ee1e0100c65034edffaf (diff) | |
download | qemu-89aec6411c429adb662c53c94a986a5397961a7f.zip qemu-89aec6411c429adb662c53c94a986a5397961a7f.tar.gz qemu-89aec6411c429adb662c53c94a986a5397961a7f.tar.bz2 |
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>
Diffstat (limited to 'util/oslib-posix.c')
-rw-r--r-- | util/oslib-posix.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/util/oslib-posix.c b/util/oslib-posix.c index cf2ead5..67c08a4 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -40,6 +40,7 @@ #include <libgen.h> #include "qemu/cutils.h" #include "qemu/compiler.h" +#include "qemu/units.h" #ifdef CONFIG_LINUX #include <sys/syscall.h> @@ -525,7 +526,8 @@ static void *do_madv_populate_write_pages(void *arg) return (void *)(uintptr_t)ret; } -static inline int get_memset_num_threads(int smp_cpus) +static inline int get_memset_num_threads(size_t hpagesize, size_t numpages, + int smp_cpus) { long host_procs = sysconf(_SC_NPROCESSORS_ONLN); int ret = 1; @@ -533,6 +535,12 @@ static inline int get_memset_num_threads(int smp_cpus) if (host_procs > 0) { ret = MIN(MIN(host_procs, MAX_MEM_PREALLOC_THREAD_COUNT), smp_cpus); } + + /* Especially with gigantic pages, don't create more threads than pages. */ + ret = MIN(ret, numpages); + /* Don't start threads to prealloc comparatively little memory. */ + ret = MIN(ret, MAX(1, hpagesize * numpages / (64 * MiB))); + /* In case sysconf() fails, we fall back to single threaded */ return ret; } @@ -542,7 +550,7 @@ static int touch_all_pages(char *area, size_t hpagesize, size_t numpages, { static gsize initialized = 0; MemsetContext context = { - .num_threads = get_memset_num_threads(smp_cpus), + .num_threads = get_memset_num_threads(hpagesize, numpages, smp_cpus), }; size_t numpages_per_thread, leftover; void *(*touch_fn)(void *); |