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CPUPhysMemoryClient: batch addresses in catchup 

When a phys memory client registers and we play catchup by walking
the page tables, we can make a huge improvement in the number of
times the set_memory callback is called by batching contiguous
pages together.  With a 4G guest, this reduces the number of callbacks
at registration from 1048866 to 296.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Alex Williamson 2011-05-03 12:36:58 -06:00 committed by Michael S. Tsirkin
parent 69c8944f17
commit 2173a75fb7
1 changed files with 33 additions and 6 deletions
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39
exec.c
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@ -1750,14 +1750,21 @@ static int cpu_notify_migration_log(int enable)
return 0;
}
struct last_map {
target_phys_addr_t start_addr;
ram_addr_t size;
ram_addr_t phys_offset;
};
/* The l1_phys_map provides the upper P_L1_BITs of the guest physical
* address. Each intermediate table provides the next L2_BITs of guest
* physical address space. The number of levels vary based on host and
* guest configuration, making it efficient to build the final guest
* physical address by seeding the L1 offset and shifting and adding in
* each L2 offset as we recurse through them. */
static void phys_page_for_each_1(CPUPhysMemoryClient *client,
int level, void **lp, target_phys_addr_t addr)
static void phys_page_for_each_1(CPUPhysMemoryClient *client, int level,
void **lp, target_phys_addr_t addr,
struct last_map *map)
{
int i;
@ -1769,15 +1776,29 @@ static void phys_page_for_each_1(CPUPhysMemoryClient *client,
addr <<= L2_BITS + TARGET_PAGE_BITS;
for (i = 0; i < L2_SIZE; ++i) {
if (pd[i].phys_offset != IO_MEM_UNASSIGNED) {
client->set_memory(client, addr | i << TARGET_PAGE_BITS,
TARGET_PAGE_SIZE, pd[i].phys_offset, false);
target_phys_addr_t start_addr = addr | i << TARGET_PAGE_BITS;
if (map->size &&
start_addr == map->start_addr + map->size &&
pd[i].phys_offset == map->phys_offset + map->size) {
map->size += TARGET_PAGE_SIZE;
continue;
} else if (map->size) {
client->set_memory(client, map->start_addr,
map->size, map->phys_offset, false);
}
map->start_addr = start_addr;
map->size = TARGET_PAGE_SIZE;
map->phys_offset = pd[i].phys_offset;
}
}
} else {
void **pp = *lp;
for (i = 0; i < L2_SIZE; ++i) {
phys_page_for_each_1(client, level - 1, pp + i,
(addr << L2_BITS) | i);
(addr << L2_BITS) | i, map);
}
}
}
@ -1785,9 +1806,15 @@ static void phys_page_for_each_1(CPUPhysMemoryClient *client,
static void phys_page_for_each(CPUPhysMemoryClient *client)
{
int i;
struct last_map map = { };
for (i = 0; i < P_L1_SIZE; ++i) {
phys_page_for_each_1(client, P_L1_SHIFT / L2_BITS - 1,
l1_phys_map + i, i);
l1_phys_map + i, i, &map);
}
if (map.size) {
client->set_memory(client, map.start_addr, map.size, map.phys_offset,
false);
}
}