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[PATCH v3 4/7] util/oslib-posix: Don't create too many threads with smal
From: |
David Hildenbrand |
Subject: |
[PATCH v3 4/7] util/oslib-posix: Don't create too many threads with small memory or little pages |
Date: |
Mon, 16 Aug 2021 11:47:36 +0200 |
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>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
util/oslib-posix.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index cf2ead54ad..67c08a425e 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 *);
--
2.31.1
- [PATCH v3 0/7] util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc(), David Hildenbrand, 2021/08/16
- [PATCH v3 1/7] util/oslib-posix: Let touch_all_pages() return an error, David Hildenbrand, 2021/08/16
- [PATCH v3 3/7] util/oslib-posix: Introduce and use MemsetContext for touch_all_pages(), David Hildenbrand, 2021/08/16
- [PATCH v3 2/7] util/oslib-posix: Support MADV_POPULATE_WRITE for os_mem_prealloc(), David Hildenbrand, 2021/08/16
- [PATCH v3 4/7] util/oslib-posix: Don't create too many threads with small memory or little pages,
David Hildenbrand <=
- [PATCH v3 5/7] util/oslib-posix: Avoid creating a single thread with MADV_POPULATE_WRITE, David Hildenbrand, 2021/08/16
- [PATCH v3 7/7] util/oslib-posix: Forward SIGBUS to MCE handler under Linux, David Hildenbrand, 2021/08/16
- [PATCH v3 6/7] util/oslib-posix: Support concurrent os_mem_prealloc() invocation, David Hildenbrand, 2021/08/16