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Re: [Qemu-devel] [PATCH 45/51] ram: Use page number instead of an addres
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 45/51] ram: Use page number instead of an address for the bitmap operations |
Date: |
Fri, 31 Mar 2017 13:22:33 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
* Juan Quintela (address@hidden) wrote:
> We use an unsigned long for the page number. Notice that our bitmaps
> already got that for the index, so we have that limit.
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> migration/ram.c | 76
> ++++++++++++++++++++++++++-------------------------------
> 1 file changed, 34 insertions(+), 42 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 6cd77b5..b1a031e 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -611,13 +611,12 @@ static int save_xbzrle_page(RAMState *rs, uint8_t
> **current_data,
> * @rs: current RAM state
> * @rb: RAMBlock where to search for dirty pages
> * @start: starting address (typically so we can continue from previous page)
> - * @ram_addr_abs: pointer into which to store the address of the dirty page
> - * within the global ram_addr space
> + * @page: pointer into where to store the dirty page
I'd prefer if you could call it 'page_abs' - it often gets tricky to know
whether we're talking about a page offset within a RAMBlock or an offset within
the whole bitmap.
(I wish we had different index types)
> */
> static inline
> ram_addr_t migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb,
> ram_addr_t start,
> - ram_addr_t *ram_addr_abs)
> + unsigned long *page)
> {
> unsigned long base = rb->offset >> TARGET_PAGE_BITS;
> unsigned long nr = base + (start >> TARGET_PAGE_BITS);
> @@ -634,17 +633,17 @@ ram_addr_t migration_bitmap_find_dirty(RAMState *rs,
> RAMBlock *rb,
> next = find_next_bit(bitmap, size, nr);
> }
>
> - *ram_addr_abs = next << TARGET_PAGE_BITS;
> + *page = next;
> return (next - base) << TARGET_PAGE_BITS;
> }
>
> -static inline bool migration_bitmap_clear_dirty(RAMState *rs, ram_addr_t
> addr)
> +static inline bool migration_bitmap_clear_dirty(RAMState *rs,
> + unsigned long page)
> {
> bool ret;
> - int nr = addr >> TARGET_PAGE_BITS;
> unsigned long *bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
>
> - ret = test_and_clear_bit(nr, bitmap);
> + ret = test_and_clear_bit(page, bitmap);
>
> if (ret) {
> rs->migration_dirty_pages--;
> @@ -1056,14 +1055,13 @@ static int ram_save_compressed_page(RAMState *rs,
> PageSearchStatus *pss,
> * @rs: current RAM state
> * @pss: data about the state of the current dirty page scan
> * @again: set to false if the search has scanned the whole of RAM
> - * @ram_addr_abs: pointer into which to store the address of the dirty page
> - * within the global ram_addr space
> + * @page: pointer into where to store the dirty page
> */
> static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss,
> - bool *again, ram_addr_t *ram_addr_abs)
> + bool *again, unsigned long *page)
> {
> pss->offset = migration_bitmap_find_dirty(rs, pss->block, pss->offset,
> - ram_addr_abs);
> + page);
> if (pss->complete_round && pss->block == rs->last_seen_block &&
> pss->offset >= rs->last_offset) {
> /*
> @@ -1111,11 +1109,10 @@ static bool find_dirty_block(RAMState *rs,
> PageSearchStatus *pss,
> *
> * @rs: current RAM state
> * @offset: used to return the offset within the RAMBlock
> - * @ram_addr_abs: pointer into which to store the address of the dirty page
> - * within the global ram_addr space
> + * @page: pointer into where to store the dirty page
> */
> static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset,
> - ram_addr_t *ram_addr_abs)
> + unsigned long *page)
> {
> RAMBlock *block = NULL;
>
> @@ -1125,8 +1122,7 @@ static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t
> *offset,
> QSIMPLEQ_FIRST(&rs->src_page_requests);
> block = entry->rb;
> *offset = entry->offset;
> - *ram_addr_abs = (entry->offset + entry->rb->offset) &
> - TARGET_PAGE_MASK;
> + *page = (entry->offset + entry->rb->offset) >> TARGET_PAGE_BITS;
>
> if (entry->len > TARGET_PAGE_SIZE) {
> entry->len -= TARGET_PAGE_SIZE;
> @@ -1151,18 +1147,17 @@ static RAMBlock *unqueue_page(RAMState *rs,
> ram_addr_t *offset,
> *
> * @rs: current RAM state
> * @pss: data about the state of the current dirty page scan
> - * @ram_addr_abs: pointer into which to store the address of the dirty page
> - * within the global ram_addr space
> + * @page: pointer into where to store the dirty page
> */
> static bool get_queued_page(RAMState *rs, PageSearchStatus *pss,
> - ram_addr_t *ram_addr_abs)
> + unsigned long *page)
> {
> RAMBlock *block;
> ram_addr_t offset;
> bool dirty;
>
> do {
> - block = unqueue_page(rs, &offset, ram_addr_abs);
> + block = unqueue_page(rs, &offset, page);
> /*
> * We're sending this page, and since it's postcopy nothing else
> * will dirty it, and we must make sure it doesn't get sent again
> @@ -1172,17 +1167,15 @@ static bool get_queued_page(RAMState *rs,
> PageSearchStatus *pss,
> if (block) {
> unsigned long *bitmap;
> bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
> - dirty = test_bit(*ram_addr_abs >> TARGET_PAGE_BITS, bitmap);
> + dirty = test_bit(*page, bitmap);
> if (!dirty) {
> - trace_get_queued_page_not_dirty(
> - block->idstr, (uint64_t)offset,
> - (uint64_t)*ram_addr_abs,
> - test_bit(*ram_addr_abs >> TARGET_PAGE_BITS,
> - atomic_rcu_read(&rs->ram_bitmap)->unsentmap));
> + trace_get_queued_page_not_dirty(block->idstr,
> (uint64_t)offset,
> + *page,
> + test_bit(*page,
> + atomic_rcu_read(&rs->ram_bitmap)->unsentmap));
> } else {
> - trace_get_queued_page(block->idstr,
> - (uint64_t)offset,
> - (uint64_t)*ram_addr_abs);
> + trace_get_queued_page(block->idstr, (uint64_t)offset,
> + *page);
I think you need to fix the trace_ definitions for get_queued_page
and get_queued_page_not_dirty they're currently taking uint64_t's for
ram_addr and they now need to be long's (with the format changes).
Dave
> }
> }
>
> @@ -1308,15 +1301,15 @@ err:
> * @ms: current migration state
> * @pss: data about the page we want to send
> * @last_stage: if we are at the completion stage
> - * @dirty_ram_abs: address of the start of the dirty page in ram_addr_t space
> + * @page: page number of the dirty page
> */
> static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
> - bool last_stage, ram_addr_t dirty_ram_abs)
> + bool last_stage, unsigned long page)
> {
> int res = 0;
>
> /* Check the pages is dirty and if it is send it */
> - if (migration_bitmap_clear_dirty(rs, dirty_ram_abs)) {
> + if (migration_bitmap_clear_dirty(rs, page)) {
> unsigned long *unsentmap;
> if (!rs->preffer_xbzrle && migrate_use_compression()) {
> res = ram_save_compressed_page(rs, pss, last_stage);
> @@ -1329,7 +1322,7 @@ static int ram_save_target_page(RAMState *rs,
> PageSearchStatus *pss,
> }
> unsentmap = atomic_rcu_read(&rs->ram_bitmap)->unsentmap;
> if (unsentmap) {
> - clear_bit(dirty_ram_abs >> TARGET_PAGE_BITS, unsentmap);
> + clear_bit(page, unsentmap);
> }
> }
>
> @@ -1351,24 +1344,24 @@ static int ram_save_target_page(RAMState *rs,
> PageSearchStatus *pss,
> * @ms: current migration state
> * @pss: data about the page we want to send
> * @last_stage: if we are at the completion stage
> - * @dirty_ram_abs: Address of the start of the dirty page in ram_addr_t space
> + * @page: Page number of the dirty page
> */
> static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss,
> bool last_stage,
> - ram_addr_t dirty_ram_abs)
> + unsigned long page)
> {
> int tmppages, pages = 0;
> size_t pagesize = qemu_ram_pagesize(pss->block);
>
> do {
> - tmppages = ram_save_target_page(rs, pss, last_stage, dirty_ram_abs);
> + tmppages = ram_save_target_page(rs, pss, last_stage, page);
> if (tmppages < 0) {
> return tmppages;
> }
>
> pages += tmppages;
> pss->offset += TARGET_PAGE_SIZE;
> - dirty_ram_abs += TARGET_PAGE_SIZE;
> + page++;
> } while (pss->offset & (pagesize - 1));
>
> /* The offset we leave with is the last one we looked at */
> @@ -1395,8 +1388,7 @@ static int ram_find_and_save_block(RAMState *rs, bool
> last_stage)
> PageSearchStatus pss;
> int pages = 0;
> bool again, found;
> - ram_addr_t dirty_ram_abs; /* Address of the start of the dirty page in
> - ram_addr_t space */
> + unsigned long page; /* Page number of the dirty page */
>
> /* No dirty page as there is zero RAM */
> if (!ram_bytes_total()) {
> @@ -1413,15 +1405,15 @@ static int ram_find_and_save_block(RAMState *rs, bool
> last_stage)
>
> do {
> again = true;
> - found = get_queued_page(rs, &pss, &dirty_ram_abs);
> + found = get_queued_page(rs, &pss, &page);
>
> if (!found) {
> /* priority queue empty, so just search for something dirty */
> - found = find_dirty_block(rs, &pss, &again, &dirty_ram_abs);
> + found = find_dirty_block(rs, &pss, &again, &page);
> }
>
> if (found) {
> - pages = ram_save_host_page(rs, &pss, last_stage, dirty_ram_abs);
> + pages = ram_save_host_page(rs, &pss, last_stage, page);
> }
> } while (!pages && again);
>
> --
> 2.9.3
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH 42/51] ram: Pass RAMBlock to bitmap_sync, (continued)
Re: [Qemu-devel] [PATCH 42/51] ram: Pass RAMBlock to bitmap_sync, Dr. David Alan Gilbert, 2017/03/30
[Qemu-devel] [PATCH 45/51] ram: Use page number instead of an address for the bitmap operations, Juan Quintela, 2017/03/23
- Re: [Qemu-devel] [PATCH 45/51] ram: Use page number instead of an address for the bitmap operations,
Dr. David Alan Gilbert <=
[Qemu-devel] [PATCH 43/51] ram: ram_discard_range() don't use the mis parameter, Juan Quintela, 2017/03/23
[Qemu-devel] [PATCH 46/51] ram: Remember last_page instead of last_offset, Juan Quintela, 2017/03/23
[Qemu-devel] [PATCH 47/51] ram: Change offset field in PageSearchStatus to page, Juan Quintela, 2017/03/23
[Qemu-devel] [PATCH 44/51] ram: reorganize last_sent_block, Juan Quintela, 2017/03/23