* [Qemu-devel] [PATCH v2 1/2] Move dirty page search state into separate structure
2015-09-23 14:27 [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block Dr. David Alan Gilbert (git)
@ 2015-09-23 14:27 ` Dr. David Alan Gilbert (git)
2015-09-23 14:27 ` [Qemu-devel] [PATCH v2 2/2] ram_find_and_save_block: Split out the finding Dr. David Alan Gilbert (git)
2015-09-24 3:56 ` [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block Amit Shah
2 siblings, 0 replies; 5+ messages in thread
From: Dr. David Alan Gilbert (git) @ 2015-09-23 14:27 UTC (permalink / raw)
To: qemu-devel; +Cc: amit.shah, quintela
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Pull the search state for one iteration of the dirty page
search into a structure.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
---
migration/ram.c | 55 +++++++++++++++++++++++++++++++++++--------------------
1 file changed, 35 insertions(+), 20 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 7df9157..d79d79d 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -227,6 +227,17 @@ static uint64_t migration_dirty_pages;
static uint32_t last_version;
static bool ram_bulk_stage;
+/* used by the search for pages to send */
+struct PageSearchStatus {
+ /* Current block being searched */
+ RAMBlock *block;
+ /* Current offset to search from */
+ ram_addr_t offset;
+ /* Set once we wrap around */
+ bool complete_round;
+};
+typedef struct PageSearchStatus PageSearchStatus;
+
struct CompressParam {
bool start;
bool done;
@@ -531,7 +542,6 @@ static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length)
cpu_physical_memory_sync_dirty_bitmap(bitmap, start, length);
}
-
/* Fix me: there are too many global variables used in migration process. */
static int64_t start_time;
static int64_t bytes_xfer_prev;
@@ -923,26 +933,30 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
uint64_t *bytes_transferred)
{
- RAMBlock *block = last_seen_block;
- ram_addr_t offset = last_offset;
- bool complete_round = false;
+ PageSearchStatus pss;
int pages = 0;
- if (!block)
- block = QLIST_FIRST_RCU(&ram_list.blocks);
+ pss.block = last_seen_block;
+ pss.offset = last_offset;
+ pss.complete_round = false;
+
+ if (!pss.block) {
+ pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
+ }
while (true) {
- offset = migration_bitmap_find_and_reset_dirty(block, offset);
- if (complete_round && block == last_seen_block &&
- offset >= last_offset) {
+ pss.offset = migration_bitmap_find_and_reset_dirty(pss.block,
+ pss.offset);
+ if (pss.complete_round && pss.block == last_seen_block &&
+ pss.offset >= last_offset) {
break;
}
- if (offset >= block->used_length) {
- offset = 0;
- block = QLIST_NEXT_RCU(block, next);
- if (!block) {
- block = QLIST_FIRST_RCU(&ram_list.blocks);
- complete_round = true;
+ if (pss.offset >= pss.block->used_length) {
+ pss.offset = 0;
+ pss.block = QLIST_NEXT_RCU(pss.block, next);
+ if (!pss.block) {
+ pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
+ pss.complete_round = true;
ram_bulk_stage = false;
if (migrate_use_xbzrle()) {
/* If xbzrle is on, stop using the data compression at this
@@ -954,23 +968,24 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
}
} else {
if (compression_switch && migrate_use_compression()) {
- pages = ram_save_compressed_page(f, block, offset, last_stage,
+ pages = ram_save_compressed_page(f, pss.block, pss.offset,
+ last_stage,
bytes_transferred);
} else {
- pages = ram_save_page(f, block, offset, last_stage,
+ pages = ram_save_page(f, pss.block, pss.offset, last_stage,
bytes_transferred);
}
/* if page is unmodified, continue to the next */
if (pages > 0) {
- last_sent_block = block;
+ last_sent_block = pss.block;
break;
}
}
}
- last_seen_block = block;
- last_offset = offset;
+ last_seen_block = pss.block;
+ last_offset = pss.offset;
return pages;
}
--
2.5.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [Qemu-devel] [PATCH v2 2/2] ram_find_and_save_block: Split out the finding
2015-09-23 14:27 [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block Dr. David Alan Gilbert (git)
2015-09-23 14:27 ` [Qemu-devel] [PATCH v2 1/2] Move dirty page search state into separate structure Dr. David Alan Gilbert (git)
@ 2015-09-23 14:27 ` Dr. David Alan Gilbert (git)
2015-09-24 3:57 ` Amit Shah
2015-09-24 3:56 ` [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block Amit Shah
2 siblings, 1 reply; 5+ messages in thread
From: Dr. David Alan Gilbert (git) @ 2015-09-23 14:27 UTC (permalink / raw)
To: qemu-devel; +Cc: amit.shah, quintela
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Split out the finding of the dirty page and all the wrap detection
into a separate function since it was getting a bit hairy.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
migration/ram.c | 84 ++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 59 insertions(+), 25 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index d79d79d..ba2b693 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -917,6 +917,59 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock *block,
return pages;
}
+/*
+ * Find the next dirty page and update any state associated with
+ * the search process.
+ *
+ * Returns: True if a page is found
+ *
+ * @f: Current migration stream.
+ * @pss: Data about the state of the current dirty page scan.
+ * @*again: Set to false if the search has scanned the whole of RAM
+ */
+static bool find_dirty_block(QEMUFile *f, PageSearchStatus *pss,
+ bool *again)
+{
+ pss->offset = migration_bitmap_find_and_reset_dirty(pss->block,
+ pss->offset);
+ if (pss->complete_round && pss->block == last_seen_block &&
+ pss->offset >= last_offset) {
+ /*
+ * We've been once around the RAM and haven't found anything
+ * give up.
+ */
+ *again = false;
+ return false;
+ }
+ if (pss->offset >= pss->block->used_length) {
+ /* Didn't find anything in this RAM Block */
+ pss->offset = 0;
+ pss->block = QLIST_NEXT_RCU(pss->block, next);
+ if (!pss->block) {
+ /* Hit the end of the list */
+ pss->block = QLIST_FIRST_RCU(&ram_list.blocks);
+ /* Flag that we've looped */
+ pss->complete_round = true;
+ ram_bulk_stage = false;
+ if (migrate_use_xbzrle()) {
+ /* If xbzrle is on, stop using the data compression at this
+ * point. In theory, xbzrle can do better than compression.
+ */
+ flush_compressed_data(f);
+ compression_switch = false;
+ }
+ }
+ /* Didn't find anything this time, but try again on the new block */
+ *again = true;
+ return false;
+ } else {
+ /* Can go around again, but... */
+ *again = true;
+ /* We've found something so probably don't need to */
+ return true;
+ }
+}
+
/**
* ram_find_and_save_block: Finds a dirty page and sends it to f
*
@@ -935,6 +988,7 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
{
PageSearchStatus pss;
int pages = 0;
+ bool again, found;
pss.block = last_seen_block;
pss.offset = last_offset;
@@ -944,29 +998,10 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
}
- while (true) {
- pss.offset = migration_bitmap_find_and_reset_dirty(pss.block,
- pss.offset);
- if (pss.complete_round && pss.block == last_seen_block &&
- pss.offset >= last_offset) {
- break;
- }
- if (pss.offset >= pss.block->used_length) {
- pss.offset = 0;
- pss.block = QLIST_NEXT_RCU(pss.block, next);
- if (!pss.block) {
- pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
- pss.complete_round = true;
- ram_bulk_stage = false;
- if (migrate_use_xbzrle()) {
- /* If xbzrle is on, stop using the data compression at this
- * point. In theory, xbzrle can do better than compression.
- */
- flush_compressed_data(f);
- compression_switch = false;
- }
- }
- } else {
+ do {
+ found = find_dirty_block(f, &pss, &again);
+
+ if (found) {
if (compression_switch && migrate_use_compression()) {
pages = ram_save_compressed_page(f, pss.block, pss.offset,
last_stage,
@@ -979,10 +1014,9 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage,
/* if page is unmodified, continue to the next */
if (pages > 0) {
last_sent_block = pss.block;
- break;
}
}
- }
+ } while (!pages && again);
last_seen_block = pss.block;
last_offset = pss.offset;
--
2.5.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [Qemu-devel] [PATCH v2 2/2] ram_find_and_save_block: Split out the finding
2015-09-23 14:27 ` [Qemu-devel] [PATCH v2 2/2] ram_find_and_save_block: Split out the finding Dr. David Alan Gilbert (git)
@ 2015-09-24 3:57 ` Amit Shah
0 siblings, 0 replies; 5+ messages in thread
From: Amit Shah @ 2015-09-24 3:57 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git); +Cc: qemu-devel, quintela
On (Wed) 23 Sep 2015 [15:27:11], Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Split out the finding of the dirty page and all the wrap detection
> into a separate function since it was getting a bit hairy.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> + if (pss->complete_round && pss->block == last_seen_block &&
> + pss->offset >= last_offset) {
> + /*
> + * We've been once around the RAM and haven't found anything
> + * give up.
I didn't notice this first time around - but I can fix this up while
merging. Give up should be another sentence, right?
Amit
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block
2015-09-23 14:27 [Qemu-devel] [PATCH v2 0/2] Split up ram_find_and_save_block Dr. David Alan Gilbert (git)
2015-09-23 14:27 ` [Qemu-devel] [PATCH v2 1/2] Move dirty page search state into separate structure Dr. David Alan Gilbert (git)
2015-09-23 14:27 ` [Qemu-devel] [PATCH v2 2/2] ram_find_and_save_block: Split out the finding Dr. David Alan Gilbert (git)
@ 2015-09-24 3:56 ` Amit Shah
2 siblings, 0 replies; 5+ messages in thread
From: Amit Shah @ 2015-09-24 3:56 UTC (permalink / raw)
To: Dr. David Alan Gilbert (git); +Cc: qemu-devel, quintela
On (Wed) 23 Sep 2015 [15:27:09], Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Chop up ram_find_and_save_block so it's smaller again.
> (from comments on my postcopy patch that adds more to it).
>
> This pair is based on top of my previous 5 patch cleanup series posted
> in August, but rebased on current qemu master.
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Amit
^ permalink raw reply [flat|nested] 5+ messages in thread