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[Qemu-devel] [Patch v2] migration/postcopy: make PostcopyDiscardState a
From: |
Wei Yang |
Subject: |
[Qemu-devel] [Patch v2] migration/postcopy: make PostcopyDiscardState a static variable |
Date: |
Wed, 24 Jul 2019 09:07:21 +0800 |
In postcopy-ram.c, we provide three functions to discard certain
RAMBlock range:
* postcopy_discard_send_init()
* postcopy_discard_send_range()
* postcopy_discard_send_finish()
Currently, we allocate/deallocate PostcopyDiscardState for each RAMBlock
on sending discard information to destination. This is not necessary and
the same data area could be reused for each RAMBlock.
This patch defines PostcopyDiscardState a static variable. By doing so:
1) avoid memory allocation and deallocation to the system
2) avoid potential failure of memory allocation
3) hide some details for their users
Signed-off-by: Wei Yang <address@hidden>
---
v2:
* make it a static variable, suggested by Dave
---
migration/postcopy-ram.c | 70 +++++++++++++++++-----------------------
migration/postcopy-ram.h | 13 +++-----
migration/ram.c | 30 +++++++----------
3 files changed, 46 insertions(+), 67 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 7b3e198538..cf2400b47e 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1375,22 +1375,16 @@ void
postcopy_fault_thread_notify(MigrationIncomingState *mis)
* asking to discard individual ranges.
*
* @ms: The current migration state.
- * @offset: the bitmap offset of the named RAMBlock in the migration
- * bitmap.
+ * @offset: the bitmap offset of the named RAMBlock in the migration bitmap.
* @name: RAMBlock that discards will operate on.
- *
- * returns: a new PDS.
*/
-PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
- const char *name)
+static PostcopyDiscardState pds = {0};
+void postcopy_discard_send_init(MigrationState *ms, const char *name)
{
- PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState));
-
- if (res) {
- res->ramblock_name = name;
- }
-
- return res;
+ pds.ramblock_name = name;
+ pds.cur_entry = 0;
+ pds.nsentwords = 0;
+ pds.nsentcmds = 0;
}
/**
@@ -1399,30 +1393,29 @@ PostcopyDiscardState
*postcopy_discard_send_init(MigrationState *ms,
* be sent later.
*
* @ms: Current migration state.
- * @pds: Structure initialised by postcopy_discard_send_init().
* @start,@length: a range of pages in the migration bitmap in the
* RAM block passed to postcopy_discard_send_init() (length=1 is one page)
*/
-void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
- unsigned long start, unsigned long length)
+void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
+ unsigned long length)
{
size_t tp_size = qemu_target_page_size();
/* Convert to byte offsets within the RAM block */
- pds->start_list[pds->cur_entry] = start * tp_size;
- pds->length_list[pds->cur_entry] = length * tp_size;
- trace_postcopy_discard_send_range(pds->ramblock_name, start, length);
- pds->cur_entry++;
- pds->nsentwords++;
+ pds.start_list[pds.cur_entry] = start * tp_size;
+ pds.length_list[pds.cur_entry] = length * tp_size;
+ trace_postcopy_discard_send_range(pds.ramblock_name, start, length);
+ pds.cur_entry++;
+ pds.nsentwords++;
- if (pds->cur_entry == MAX_DISCARDS_PER_COMMAND) {
+ if (pds.cur_entry == MAX_DISCARDS_PER_COMMAND) {
/* Full set, ship it! */
qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
- pds->ramblock_name,
- pds->cur_entry,
- pds->start_list,
- pds->length_list);
- pds->nsentcmds++;
- pds->cur_entry = 0;
+ pds.ramblock_name,
+ pds.cur_entry,
+ pds.start_list,
+ pds.length_list);
+ pds.nsentcmds++;
+ pds.cur_entry = 0;
}
}
@@ -1431,24 +1424,21 @@ void postcopy_discard_send_range(MigrationState *ms,
PostcopyDiscardState *pds,
* bitmap code. Sends any outstanding discard messages, frees the PDS
*
* @ms: Current migration state.
- * @pds: Structure initialised by postcopy_discard_send_init().
*/
-void postcopy_discard_send_finish(MigrationState *ms, PostcopyDiscardState
*pds)
+void postcopy_discard_send_finish(MigrationState *ms)
{
/* Anything unsent? */
- if (pds->cur_entry) {
+ if (pds.cur_entry) {
qemu_savevm_send_postcopy_ram_discard(ms->to_dst_file,
- pds->ramblock_name,
- pds->cur_entry,
- pds->start_list,
- pds->length_list);
- pds->nsentcmds++;
+ pds.ramblock_name,
+ pds.cur_entry,
+ pds.start_list,
+ pds.length_list);
+ pds.nsentcmds++;
}
- trace_postcopy_discard_send_finish(pds->ramblock_name, pds->nsentwords,
- pds->nsentcmds);
-
- g_free(pds);
+ trace_postcopy_discard_send_finish(pds.ramblock_name, pds.nsentwords,
+ pds.nsentcmds);
}
/*
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index e3a5cfd2d8..e3dde32155 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -43,10 +43,8 @@ int postcopy_ram_prepare_discard(MigrationIncomingState
*mis);
/*
* Called at the start of each RAMBlock by the bitmap code.
- * Returns a new PDS
*/
-PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
- const char *name);
+void postcopy_discard_send_init(MigrationState *ms, const char *name);
/*
* Called by the bitmap code for each chunk to discard.
@@ -55,15 +53,14 @@ PostcopyDiscardState
*postcopy_discard_send_init(MigrationState *ms,
* @start,@length: a range of pages in the migration bitmap in the
* RAM block passed to postcopy_discard_send_init() (length=1 is one page)
*/
-void postcopy_discard_send_range(MigrationState *ms, PostcopyDiscardState *pds,
- unsigned long start, unsigned long length);
+void postcopy_discard_send_range(MigrationState *ms, unsigned long start,
+ unsigned long length);
/*
* Called at the end of each RAMBlock by the bitmap code.
- * Sends any outstanding discard messages, frees the PDS.
+ * Sends any outstanding discard messages.
*/
-void postcopy_discard_send_finish(MigrationState *ms,
- PostcopyDiscardState *pds);
+void postcopy_discard_send_finish(MigrationState *ms);
/*
* Place a page (from) at (host) efficiently
diff --git a/migration/ram.c b/migration/ram.c
index ecd10baa43..7b7155a368 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2761,12 +2761,9 @@ void ram_postcopy_migrated_memory_release(MigrationState
*ms)
* with the dirtymap; so a '1' means it's either dirty or unsent.
*
* @ms: current migration state
- * @pds: state for postcopy
* @block: RAMBlock to discard
*/
-static int postcopy_send_discard_bm_ram(MigrationState *ms,
- PostcopyDiscardState *pds,
- RAMBlock *block)
+static int postcopy_send_discard_bm_ram(MigrationState *ms, RAMBlock *block)
{
unsigned long end = block->used_length >> TARGET_PAGE_BITS;
unsigned long current;
@@ -2787,7 +2784,7 @@ static int postcopy_send_discard_bm_ram(MigrationState
*ms,
} else {
discard_length = zero - one;
}
- postcopy_discard_send_range(ms, pds, one, discard_length);
+ postcopy_discard_send_range(ms, one, discard_length);
current = one + discard_length;
}
@@ -2813,16 +2810,15 @@ static int
postcopy_each_ram_send_discard(MigrationState *ms)
int ret;
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
- PostcopyDiscardState *pds =
- postcopy_discard_send_init(ms, block->idstr);
+ postcopy_discard_send_init(ms, block->idstr);
/*
* Postcopy sends chunks of bitmap over the wire, but it
* just needs indexes at this point, avoids it having
* target page specific code.
*/
- ret = postcopy_send_discard_bm_ram(ms, pds, block);
- postcopy_discard_send_finish(ms, pds);
+ ret = postcopy_send_discard_bm_ram(ms, block);
+ postcopy_discard_send_finish(ms);
if (ret) {
return ret;
}
@@ -2845,11 +2841,9 @@ static int postcopy_each_ram_send_discard(MigrationState
*ms)
* @unsent_pass: if true we need to canonicalize partially unsent host pages
* otherwise we need to canonicalize partially dirty host pages
* @block: block that contains the page we want to canonicalize
- * @pds: state for postcopy
*/
static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
- RAMBlock *block,
- PostcopyDiscardState *pds)
+ RAMBlock *block)
{
RAMState *rs = ram_state;
unsigned long *bitmap = block->bmap;
@@ -2910,8 +2904,7 @@ static void postcopy_chunk_hostpages_pass(MigrationState
*ms, bool unsent_pass,
* (any partially sent pages were already discarded
* by the previous unsent_pass)
*/
- postcopy_discard_send_range(ms, pds, fixup_start_addr,
- host_ratio);
+ postcopy_discard_send_range(ms, fixup_start_addr, host_ratio);
}
/* Clean up the bitmap */
@@ -2954,18 +2947,17 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
*/
static int postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block)
{
- PostcopyDiscardState *pds =
- postcopy_discard_send_init(ms, block->idstr);
+ postcopy_discard_send_init(ms, block->idstr);
/* First pass: Discard all partially sent host pages */
- postcopy_chunk_hostpages_pass(ms, true, block, pds);
+ postcopy_chunk_hostpages_pass(ms, true, block);
/*
* Second pass: Ensure that all partially dirty host pages are made
* fully dirty.
*/
- postcopy_chunk_hostpages_pass(ms, false, block, pds);
+ postcopy_chunk_hostpages_pass(ms, false, block);
- postcopy_discard_send_finish(ms, pds);
+ postcopy_discard_send_finish(ms);
return 0;
}
--
2.17.1
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