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migration/postcopy: make PostcopyDiscardState a static variable 

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 <richardw.yang@linux.intel.com>

Message-Id: <20190724010721.2146-1-richardw.yang@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Wei Yang 2019-07-24 09:07:21 +08:00 committed by Dr. David Alan Gilbert
parent 10da4a3689
commit 810cf2bbd4
3 changed files with 46 additions and 67 deletions
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70
migration/postcopy-ram.c
View File

@ -1377,22 +1377,16 @@ 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;
}
/**
@ -1401,30 +1395,29 @@ 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;
}
}
@ -1433,24 +1426,21 @@ 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);
}
/*

13
migration/postcopy-ram.h
View File

@ -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

30
migration/ram.c
View File

@ -2850,12 +2850,9 @@ 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;
@ -2876,7 +2873,7 @@ 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;
}
@ -2902,16 +2899,15 @@ 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;
}
@ -2934,11 +2930,9 @@ 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;
@ -3018,8 +3012,7 @@ 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 */
@ -3062,18 +3055,17 @@ 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;
}