friedkiwi/qemu
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

migration/savevm: use stack-allocated bitmap in configuration_validate_capabilities

Browse Source 
configuration_validate_capabilities() allocates a bitmap on the heap
to track source capabilities via bitmap_new()/g_free().  Since
MIGRATION_CAPABILITY__MAX is a small compile-time constant (< 64),
a heap allocation for a bitmap this small is wasteful: it adds
malloc/free overhead and a potential cache miss for a transient
8-byte allocation.

Replace with DECLARE_BITMAP() on the stack and bitmap_zero() to
initialize.  This eliminates the heap round-trip entirely.

Signed-off-by: Bin Guo <guobin@linux.alibaba.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20260518110112.21395-5-guobin@linux.alibaba.com
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Bin Guo
2026-05-18 19:01:08 +08:00
committed by Peter Xu
parent 36dec7c619
commit a5225ba9ee
1 changed files with 2 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
migration/savevm.c
View File

@@ -347,10 +347,10 @@ static bool configuration_validate_capabilities(SaveState *state)
{
bool ret = true;
MigrationState *s = migrate_get_current();
unsigned long *source_caps_bm;
DECLARE_BITMAP(source_caps_bm, MIGRATION_CAPABILITY__MAX);
int i;
source_caps_bm = bitmap_new(MIGRATION_CAPABILITY__MAX);
bitmap_zero(source_caps_bm, MIGRATION_CAPABILITY__MAX);
for (i = 0; i < state->caps_count; i++) {
MigrationCapability capability = state->capabilities[i];
set_bit(capability, source_caps_bm);
@@ -373,7 +373,6 @@ static bool configuration_validate_capabilities(SaveState *state)
}
}
g_free(source_caps_bm);
return ret;
}