From: Emilio Cota <cota@braap.org>
To: qemu-devel@nongnu.org
Cc: "Alex Bennée" <alex.bennee@linaro.org>,
"Daniel P . Berrangé" <berrange@redhat.com>,
"Emilio Cota" <cota@braap.org>
Subject: [PATCH 2/2] tcg: use QTree instead of GTree
Date: Tue, 10 Jan 2023 22:55:36 -0500 [thread overview]
Message-ID: <20230111035536.309885-3-cota@braap.org> (raw)
In-Reply-To: <20230111035536.309885-1-cota@braap.org>
qemu-user can hang in a multi-threaded fork. One common
reason is that when creating a TB, between fork and exec
we manipulate a GTree whose memory allocator (GSlice) is
not fork-safe.
Although POSIX does not mandate it, the system's allocator
(e.g. tcmalloc, libc malloc) is probably fork-safe.
Fix some of these hangs by using QTree, which uses
the system's allocator.
For more details, see:
https://gitlab.com/qemu-project/qemu/-/issues/285
Performance impact on linux-user:
- ~2% slowdown in spec06
- 1.05% slowdown in Nbench-int
- 4.51% slowdown in Nbench-fp
x86_64 spec06
Host: AMD Ryzen 7 PRO 5850U with Radeon Graphics
1.04 +--------------------------------------------------------------------------------------------------+
| | |
| qtree-gcc1|.int |
| +-+ | |
1.02 |-+...............................................|..................................|...........+-|
| | | |
| +-+ | | |
1 |-+..........+-+............|............+-+......|..........................+-+.....|...........+-|
| **|** | *|** | *+-+ | | |
| *+-+* | +-+* | * * +-+ **|** | |
| * * +-+ *|** * * **|* * * | *+-+* | +-+ |
0.98 |-+.........*...*....|.....*|.*..........*..*...*.|*...*..*...**|*..........*...*....|....**|**..+-|
| * * **|** *| * +-+ * * * |* * * *+-+ +-+ * * **|** *+-+* |
| *+-+* * * * | * +-+* | * * * |* * * * * | * * * | * * * |
| *+-+* * * *+-+* * * | * * * |* * * * * | * * * | * * * |
0.96 |-+..*...*..*...*..*...*...*..*...*|**...*..*...*.|*...*..*...*..*.....|....*...*..*.|.*..*...*..+-|
| * * * * * * * * *| * * * * |* * * * * **|* * * * | * * * |
| * * * * * * * * +-+* * * *+-+ * * * * * |* * * * | * * * |
| * * * * * * * * * * * * * * * * * * * |* * * * | * * * |
0.94 |-+..*...*..*...*..*...*...*..*...*..*...*..*...*..*...*..*...*..*...*.|*...*...*..*.|.*..*...*..+-|
| * * * * * * * * * * * * * * * * * * * |* * * * | * * * |
| * * * * * * * * * * * * * * * * * * *+-+ * * * | * * * |
0.92 |-+..*...*..*...*..*...*...*..*...*..*...*..*...*..*...*..*...*..*...*..*...*...*..*.|.*..*...*..+-|
| * * * * * * * * * * * * * * * * * * * * * * *+-+* * * |
| * * * * * * * * * * * * * * * * * * * * * * * * * * |
| * * * * * * * * * * * * * * * * * * * * * * * * * * |
0.9 +--------------------------------------------------------------------------------------------------+
400.perlben401.bzip2403.gcc429.m445.gob456.hmme45462.libqua464.h26471.omnet473483.xalancbmkgeomean
aarch64 NBench Integer Performance
Host: AMD Ryzen 7 PRO 5850U with Radeon Graphics
81.2 +----------------------------------------------------------------+
| + + |
| *** |
81 |-+ B +-|
| **## |
80.8 |-+ ## +-|
| ## |
| ## |
80.6 |-+ ## +-|
| ## |
| ## |
80.4 |-+ ## +-|
| ## |
80.2 |-+ ##** +-|
| B |
| + * |
80 +----------------------------------------------------------------+
master-gcc12 qtree-gcc12
QEMU version
aarch64 NBench Floating Point Performance
Host: AMD Ryzen 7 PRO 5850U with Radeon Graphics
13.8 +----------------------------------------------------------------+
| *B* + |
13.7 |-+ **## +-|
| ## |
13.6 |-+ # +-|
| ## |
13.5 |-+ # +-|
| ## |
13.4 |-+ ## +-|
| # |
13.3 |-+ ## +-|
| # |
13.2 |-+ ## +-|
| ##** |
13.1 |-+ B +-|
| + *** |
13 +----------------------------------------------------------------+
master-gcc12 qtree-gcc12
QEMU version
Signed-off-by: Emilio Cota <cota@braap.org>
---
accel/tcg/tb-maint.c | 17 +++++++++--------
tcg/region.c | 19 ++++++++++---------
2 files changed, 19 insertions(+), 17 deletions(-)
diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
index b3d6529ae2..e6370ddc71 100644
--- a/accel/tcg/tb-maint.c
+++ b/accel/tcg/tb-maint.c
@@ -19,6 +19,7 @@
#include "qemu/osdep.h"
#include "qemu/interval-tree.h"
+#include "qemu/qtree.h"
#include "exec/cputlb.h"
#include "exec/log.h"
#include "exec/exec-all.h"
@@ -313,7 +314,7 @@ struct page_entry {
* See also: page_collection_lock().
*/
struct page_collection {
- GTree *tree;
+ QTree *tree;
struct page_entry *max;
};
@@ -466,7 +467,7 @@ static bool page_trylock_add(struct page_collection *set, tb_page_addr_t addr)
struct page_entry *pe;
PageDesc *pd;
- pe = g_tree_lookup(set->tree, &index);
+ pe = q_tree_lookup(set->tree, &index);
if (pe) {
return false;
}
@@ -477,7 +478,7 @@ static bool page_trylock_add(struct page_collection *set, tb_page_addr_t addr)
}
pe = page_entry_new(pd, index);
- g_tree_insert(set->tree, &pe->index, pe);
+ q_tree_insert(set->tree, &pe->index, pe);
/*
* If this is either (1) the first insertion or (2) a page whose index
@@ -524,13 +525,13 @@ static struct page_collection *page_collection_lock(tb_page_addr_t start,
end >>= TARGET_PAGE_BITS;
g_assert(start <= end);
- set->tree = g_tree_new_full(tb_page_addr_cmp, NULL, NULL,
+ set->tree = q_tree_new_full(tb_page_addr_cmp, NULL, NULL,
page_entry_destroy);
set->max = NULL;
assert_no_pages_locked();
retry:
- g_tree_foreach(set->tree, page_entry_lock, NULL);
+ q_tree_foreach(set->tree, page_entry_lock, NULL);
for (index = start; index <= end; index++) {
TranslationBlock *tb;
@@ -541,7 +542,7 @@ static struct page_collection *page_collection_lock(tb_page_addr_t start,
continue;
}
if (page_trylock_add(set, index << TARGET_PAGE_BITS)) {
- g_tree_foreach(set->tree, page_entry_unlock, NULL);
+ q_tree_foreach(set->tree, page_entry_unlock, NULL);
goto retry;
}
assert_page_locked(pd);
@@ -550,7 +551,7 @@ static struct page_collection *page_collection_lock(tb_page_addr_t start,
(tb_page_addr1(tb) != -1 &&
page_trylock_add(set, tb_page_addr1(tb)))) {
/* drop all locks, and reacquire in order */
- g_tree_foreach(set->tree, page_entry_unlock, NULL);
+ q_tree_foreach(set->tree, page_entry_unlock, NULL);
goto retry;
}
}
@@ -561,7 +562,7 @@ static struct page_collection *page_collection_lock(tb_page_addr_t start,
static void page_collection_unlock(struct page_collection *set)
{
/* entries are unlocked and freed via page_entry_destroy */
- g_tree_destroy(set->tree);
+ q_tree_destroy(set->tree);
g_free(set);
}
diff --git a/tcg/region.c b/tcg/region.c
index 88d6bb273f..bef4c4756f 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -28,6 +28,7 @@
#include "qemu/mprotect.h"
#include "qemu/memalign.h"
#include "qemu/cacheinfo.h"
+#include "qemu/qtree.h"
#include "qapi/error.h"
#include "exec/exec-all.h"
#include "tcg/tcg.h"
@@ -36,7 +37,7 @@
struct tcg_region_tree {
QemuMutex lock;
- GTree *tree;
+ QTree *tree;
/* padding to avoid false sharing is computed at run-time */
};
@@ -163,7 +164,7 @@ static void tcg_region_trees_init(void)
struct tcg_region_tree *rt = region_trees + i * tree_size;
qemu_mutex_init(&rt->lock);
- rt->tree = g_tree_new_full(tb_tc_cmp, NULL, NULL, tb_destroy);
+ rt->tree = q_tree_new_full(tb_tc_cmp, NULL, NULL, tb_destroy);
}
}
@@ -202,7 +203,7 @@ void tcg_tb_insert(TranslationBlock *tb)
g_assert(rt != NULL);
qemu_mutex_lock(&rt->lock);
- g_tree_insert(rt->tree, &tb->tc, tb);
+ q_tree_insert(rt->tree, &tb->tc, tb);
qemu_mutex_unlock(&rt->lock);
}
@@ -212,7 +213,7 @@ void tcg_tb_remove(TranslationBlock *tb)
g_assert(rt != NULL);
qemu_mutex_lock(&rt->lock);
- g_tree_remove(rt->tree, &tb->tc);
+ q_tree_remove(rt->tree, &tb->tc);
qemu_mutex_unlock(&rt->lock);
}
@@ -232,7 +233,7 @@ TranslationBlock *tcg_tb_lookup(uintptr_t tc_ptr)
}
qemu_mutex_lock(&rt->lock);
- tb = g_tree_lookup(rt->tree, &s);
+ tb = q_tree_lookup(rt->tree, &s);
qemu_mutex_unlock(&rt->lock);
return tb;
}
@@ -267,7 +268,7 @@ void tcg_tb_foreach(GTraverseFunc func, gpointer user_data)
for (i = 0; i < region.n; i++) {
struct tcg_region_tree *rt = region_trees + i * tree_size;
- g_tree_foreach(rt->tree, func, user_data);
+ q_tree_foreach(rt->tree, func, user_data);
}
tcg_region_tree_unlock_all();
}
@@ -281,7 +282,7 @@ size_t tcg_nb_tbs(void)
for (i = 0; i < region.n; i++) {
struct tcg_region_tree *rt = region_trees + i * tree_size;
- nb_tbs += g_tree_nnodes(rt->tree);
+ nb_tbs += q_tree_nnodes(rt->tree);
}
tcg_region_tree_unlock_all();
return nb_tbs;
@@ -296,8 +297,8 @@ static void tcg_region_tree_reset_all(void)
struct tcg_region_tree *rt = region_trees + i * tree_size;
/* Increment the refcount first so that destroy acts as a reset */
- g_tree_ref(rt->tree);
- g_tree_destroy(rt->tree);
+ q_tree_ref(rt->tree);
+ q_tree_destroy(rt->tree);
}
tcg_region_tree_unlock_all();
}
--
2.34.1
next prev parent reply other threads:[~2023-01-11 3:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-11 3:55 [PATCH 0/2] fix for #285 Emilio Cota
2023-01-11 3:55 ` [PATCH 1/2] util: import GTree as QTree Emilio Cota
2023-01-11 12:08 ` Daniel P. Berrangé
2023-01-29 22:28 ` Emilio Cota
2023-01-11 3:55 ` Emilio Cota [this message]
2023-01-11 12:10 ` [PATCH 2/2] tcg: use QTree instead of GTree Daniel P. Berrangé
2023-01-29 22:32 ` Emilio Cota
2023-01-11 12:34 ` Daniel P. Berrangé
2023-01-25 15:58 ` Daniel P. Berrangé
2023-01-29 22:38 ` Emilio Cota
2023-01-30 9:27 ` Daniel P. Berrangé
2023-01-30 19:09 ` Richard Henderson
2023-02-05 16:41 ` Emilio Cota
2023-01-11 12:26 ` [PATCH 0/2] fix for #285 Daniel P. Berrangé
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