From: Nikolay Borisov <nborisov@suse.com>
Implement the outgoing migration side for the 'fixed-ram' capability.
A bitmap is introduced to track which pages have been written in the
migration file. Pages are written at a fixed location for every
ramblock. Zero pages are ignored as they'd be zero in the destination
migration as well.
The migration stream is altered to put the dirty pages for a ramblock
after its header instead of having a sequential stream of pages that
follow the ramblock headers. Since all pages have a fixed location,
RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration.
Without fixed-ram (current):
ramblock 1 header|ramblock 2 header|...|RAM_SAVE_FLAG_EOS|stream of
pages (iter 1)|RAM_SAVE_FLAG_EOS|stream of pages (iter 2)|...
With fixed-ram (new):
ramblock 1 header|ramblock 1 fixed-ram header|ramblock 1 pages (fixed
offsets)|ramblock 2 header|ramblock 2 fixed-ram header|ramblock 2
pages (fixed offsets)|...|RAM_SAVE_FLAG_EOS
where:
- ramblock header: the generic information for a ramblock, such as
idstr, used_len, etc.
- ramblock fixed-ram header: the new information added by this
feature: bitmap of pages written, bitmap size and offset of pages
in the migration file.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
include/exec/ramblock.h | 8 ++++
migration/options.c | 3 --
migration/ram.c | 98 ++++++++++++++++++++++++++++++++++++-----
3 files changed, 96 insertions(+), 13 deletions(-)
diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
index 69c6a53902..e0e3f16852 100644
--- a/include/exec/ramblock.h
+++ b/include/exec/ramblock.h
@@ -44,6 +44,14 @@ struct RAMBlock {
size_t page_size;
/* dirty bitmap used during migration */
unsigned long *bmap;
+ /* shadow dirty bitmap used when migrating to a file */
+ unsigned long *shadow_bmap;
+ /*
+ * offset in the file pages belonging to this ramblock are saved,
+ * used only during migration to a file.
+ */
+ off_t bitmap_offset;
+ uint64_t pages_offset;
/* bitmap of already received pages in postcopy */
unsigned long *receivedmap;
diff --git a/migration/options.c b/migration/options.c
index 2622d8c483..9f693d909f 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -271,12 +271,9 @@ bool migrate_events(void)
bool migrate_fixed_ram(void)
{
-/*
MigrationState *s = migrate_get_current();
return s->capabilities[MIGRATION_CAPABILITY_FIXED_RAM];
-*/
- return false;
}
bool migrate_ignore_shared(void)
diff --git a/migration/ram.c b/migration/ram.c
index 92769902bb..152a03604f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1157,12 +1157,18 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss,
return 0;
}
+ stat64_add(&mig_stats.zero_pages, 1);
+
+ if (migrate_fixed_ram()) {
+ /* zero pages are not transferred with fixed-ram */
+ clear_bit(offset >> TARGET_PAGE_BITS, pss->block->shadow_bmap);
+ return 1;
+ }
+
len += save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLAG_ZERO);
qemu_put_byte(file, 0);
len += 1;
ram_release_page(pss->block->idstr, offset);
-
- stat64_add(&mig_stats.zero_pages, 1);
ram_transferred_add(len);
/*
@@ -1220,14 +1226,20 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block,
{
QEMUFile *file = pss->pss_channel;
- ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
- offset | RAM_SAVE_FLAG_PAGE));
- if (async) {
- qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
- migrate_release_ram() &&
- migration_in_postcopy());
+ if (migrate_fixed_ram()) {
+ qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE,
+ block->pages_offset + offset);
+ set_bit(offset >> TARGET_PAGE_BITS, block->shadow_bmap);
} else {
- qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
+ ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
+ offset | RAM_SAVE_FLAG_PAGE));
+ if (async) {
+ qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
+ migrate_release_ram() &&
+ migration_in_postcopy());
+ } else {
+ qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
+ }
}
ram_transferred_add(TARGET_PAGE_SIZE);
stat64_add(&mig_stats.normal_pages, 1);
@@ -2475,6 +2487,8 @@ static void ram_save_cleanup(void *opaque)
block->clear_bmap = NULL;
g_free(block->bmap);
block->bmap = NULL;
+ g_free(block->shadow_bmap);
+ block->shadow_bmap = NULL;
}
xbzrle_cleanup();
@@ -2842,6 +2856,7 @@ static void ram_list_init_bitmaps(void)
*/
block->bmap = bitmap_new(pages);
bitmap_set(block->bmap, 0, pages);
+ block->shadow_bmap = bitmap_new(block->used_length >> TARGET_PAGE_BITS);
block->clear_bmap_shift = shift;
block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
}
@@ -2979,6 +2994,44 @@ void qemu_guest_free_page_hint(void *addr, size_t len)
}
}
+#define FIXED_RAM_HDR_VERSION 1
+struct FixedRamHeader {
+ uint32_t version;
+ uint64_t page_size;
+ uint64_t bitmap_offset;
+ uint64_t pages_offset;
+ /* end of v1 */
+} QEMU_PACKED;
+
+static void fixed_ram_insert_header(QEMUFile *file, RAMBlock *block)
+{
+ g_autofree struct FixedRamHeader *header;
+ size_t header_size, bitmap_size;
+ long num_pages;
+
+ header = g_new0(struct FixedRamHeader, 1);
+ header_size = sizeof(struct FixedRamHeader);
+
+ num_pages = block->used_length >> TARGET_PAGE_BITS;
+ bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long);
+
+ /*
+ * Save the file offsets of where the bitmap and the pages should
+ * go as they are written at the end of migration and during the
+ * iterative phase, respectively.
+ */
+ block->bitmap_offset = qemu_get_offset(file) + header_size;
+ block->pages_offset = ROUND_UP(block->bitmap_offset +
+ bitmap_size, 0x100000);
+
+ header->version = cpu_to_be32(FIXED_RAM_HDR_VERSION);
+ header->page_size = cpu_to_be64(TARGET_PAGE_SIZE);
+ header->bitmap_offset = cpu_to_be64(block->bitmap_offset);
+ header->pages_offset = cpu_to_be64(block->pages_offset);
+
+ qemu_put_buffer(file, (uint8_t *) header, header_size);
+}
+
/*
* Each of ram_save_setup, ram_save_iterate and ram_save_complete has
* long-running RCU critical section. When rcu-reclaims in the code
@@ -3028,6 +3081,12 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
if (migrate_ignore_shared()) {
qemu_put_be64(f, block->mr->addr);
}
+
+ if (migrate_fixed_ram()) {
+ fixed_ram_insert_header(f, block);
+ /* prepare offset for next ramblock */
+ qemu_set_offset(f, block->pages_offset + block->used_length, SEEK_SET);
+ }
}
}
@@ -3061,6 +3120,20 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
return 0;
}
+static void ram_save_shadow_bmap(QEMUFile *f)
+{
+ RAMBlock *block;
+
+ RAMBLOCK_FOREACH_MIGRATABLE(block) {
+ long num_pages = block->used_length >> TARGET_PAGE_BITS;
+ long bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long);
+ qemu_put_buffer_at(f, (uint8_t *)block->shadow_bmap, bitmap_size,
+ block->bitmap_offset);
+ /* to catch any thread late sending pages */
+ block->shadow_bmap = NULL;
+ }
+}
+
/**
* ram_save_iterate: iterative stage for migration
*
@@ -3179,7 +3252,6 @@ out:
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
qemu_fflush(f);
ram_transferred_add(8);
-
ret = qemu_file_get_error(f);
}
if (ret < 0) {
@@ -3256,7 +3328,13 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
if (migrate_multifd() && !migrate_multifd_flush_after_each_section()) {
qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
}
+
+ if (migrate_fixed_ram()) {
+ ram_save_shadow_bmap(f);
+ }
+
qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
+
qemu_fflush(f);
return 0;
--
2.35.3On Mon, Oct 23, 2023 at 05:35:54PM -0300, Fabiano Rosas wrote:
> From: Nikolay Borisov <nborisov@suse.com>
>
> Implement the outgoing migration side for the 'fixed-ram' capability.
>
> A bitmap is introduced to track which pages have been written in the
> migration file. Pages are written at a fixed location for every
> ramblock. Zero pages are ignored as they'd be zero in the destination
> migration as well.
>
> The migration stream is altered to put the dirty pages for a ramblock
> after its header instead of having a sequential stream of pages that
> follow the ramblock headers. Since all pages have a fixed location,
> RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration.
>
> Without fixed-ram (current):
>
> ramblock 1 header|ramblock 2 header|...|RAM_SAVE_FLAG_EOS|stream of
> pages (iter 1)|RAM_SAVE_FLAG_EOS|stream of pages (iter 2)|...
Clearer to diagram this vertically I think
---------------------
| ramblock 1 header |
---------------------
| ramblock 2 header |
---------------------
| ... |
---------------------
| ramblock n header |
---------------------
| RAM_SAVE_FLAG_EOS |
---------------------
| stream of pages |
| (iter 1) |
| ... |
---------------------
| RAM_SAVE_FLAG_EOS |
---------------------
| stream of pages |
| (iter 2) |
| ... |
---------------------
| ... |
---------------------
>
> With fixed-ram (new):
>
> ramblock 1 header|ramblock 1 fixed-ram header|ramblock 1 pages (fixed
> offsets)|ramblock 2 header|ramblock 2 fixed-ram header|ramblock 2
> pages (fixed offsets)|...|RAM_SAVE_FLAG_EOS
If I'm reading the code correctly the new format has some padding
such that each "ramblock pages" region starts on a 1 MB boundary.
eg so we get:
--------------------------------
| ramblock 1 header |
--------------------------------
| ramblock 1 fixed-ram header |
--------------------------------
| padding to next 1MB boundary |
| ... |
--------------------------------
| ramblock 1 pages |
| ... |
--------------------------------
| ramblock 2 header |
--------------------------------
| ramblock 2 fixed-ram header |
--------------------------------
| padding to next 1MB boundary |
| ... |
--------------------------------
| ramblock 2 pages |
| ... |
--------------------------------
| ... |
--------------------------------
| RAM_SAVE_FLAG_EOS |
--------------------------------
| ... |
-------------------------------
>
> where:
> - ramblock header: the generic information for a ramblock, such as
> idstr, used_len, etc.
>
> - ramblock fixed-ram header: the new information added by this
> feature: bitmap of pages written, bitmap size and offset of pages
> in the migration file.
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
> include/exec/ramblock.h | 8 ++++
> migration/options.c | 3 --
> migration/ram.c | 98 ++++++++++++++++++++++++++++++++++++-----
> 3 files changed, 96 insertions(+), 13 deletions(-)
>
> diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
> index 69c6a53902..e0e3f16852 100644
> --- a/include/exec/ramblock.h
> +++ b/include/exec/ramblock.h
> @@ -44,6 +44,14 @@ struct RAMBlock {
> size_t page_size;
> /* dirty bitmap used during migration */
> unsigned long *bmap;
> + /* shadow dirty bitmap used when migrating to a file */
> + unsigned long *shadow_bmap;
> + /*
> + * offset in the file pages belonging to this ramblock are saved,
> + * used only during migration to a file.
> + */
> + off_t bitmap_offset;
> + uint64_t pages_offset;
> /* bitmap of already received pages in postcopy */
> unsigned long *receivedmap;
>
> diff --git a/migration/options.c b/migration/options.c
> index 2622d8c483..9f693d909f 100644
> --- a/migration/options.c
> +++ b/migration/options.c
> @@ -271,12 +271,9 @@ bool migrate_events(void)
>
> bool migrate_fixed_ram(void)
> {
> -/*
> MigrationState *s = migrate_get_current();
>
> return s->capabilities[MIGRATION_CAPABILITY_FIXED_RAM];
> -*/
> - return false;
> }
>
> bool migrate_ignore_shared(void)
> diff --git a/migration/ram.c b/migration/ram.c
> index 92769902bb..152a03604f 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1157,12 +1157,18 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss,
> return 0;
> }
>
> + stat64_add(&mig_stats.zero_pages, 1);
> +
> + if (migrate_fixed_ram()) {
> + /* zero pages are not transferred with fixed-ram */
> + clear_bit(offset >> TARGET_PAGE_BITS, pss->block->shadow_bmap);
> + return 1;
> + }
> +
> len += save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLAG_ZERO);
> qemu_put_byte(file, 0);
> len += 1;
> ram_release_page(pss->block->idstr, offset);
> -
> - stat64_add(&mig_stats.zero_pages, 1);
> ram_transferred_add(len);
>
> /*
> @@ -1220,14 +1226,20 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block,
> {
> QEMUFile *file = pss->pss_channel;
>
> - ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
> - offset | RAM_SAVE_FLAG_PAGE));
> - if (async) {
> - qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
> - migrate_release_ram() &&
> - migration_in_postcopy());
> + if (migrate_fixed_ram()) {
> + qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE,
> + block->pages_offset + offset);
> + set_bit(offset >> TARGET_PAGE_BITS, block->shadow_bmap);
> } else {
> - qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
> + ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
> + offset | RAM_SAVE_FLAG_PAGE));
> + if (async) {
> + qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
> + migrate_release_ram() &&
> + migration_in_postcopy());
> + } else {
> + qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
> + }
> }
> ram_transferred_add(TARGET_PAGE_SIZE);
> stat64_add(&mig_stats.normal_pages, 1);
> @@ -2475,6 +2487,8 @@ static void ram_save_cleanup(void *opaque)
> block->clear_bmap = NULL;
> g_free(block->bmap);
> block->bmap = NULL;
> + g_free(block->shadow_bmap);
> + block->shadow_bmap = NULL;
> }
>
> xbzrle_cleanup();
> @@ -2842,6 +2856,7 @@ static void ram_list_init_bitmaps(void)
> */
> block->bmap = bitmap_new(pages);
> bitmap_set(block->bmap, 0, pages);
> + block->shadow_bmap = bitmap_new(block->used_length >> TARGET_PAGE_BITS);
> block->clear_bmap_shift = shift;
> block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
> }
> @@ -2979,6 +2994,44 @@ void qemu_guest_free_page_hint(void *addr, size_t len)
> }
> }
>
> +#define FIXED_RAM_HDR_VERSION 1
> +struct FixedRamHeader {
> + uint32_t version;
> + uint64_t page_size;
> + uint64_t bitmap_offset;
> + uint64_t pages_offset;
> + /* end of v1 */
> +} QEMU_PACKED;
> +
> +static void fixed_ram_insert_header(QEMUFile *file, RAMBlock *block)
> +{
> + g_autofree struct FixedRamHeader *header;
> + size_t header_size, bitmap_size;
> + long num_pages;
> +
> + header = g_new0(struct FixedRamHeader, 1);
> + header_size = sizeof(struct FixedRamHeader);
> +
> + num_pages = block->used_length >> TARGET_PAGE_BITS;
> + bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long);
> +
> + /*
> + * Save the file offsets of where the bitmap and the pages should
> + * go as they are written at the end of migration and during the
> + * iterative phase, respectively.
> + */
> + block->bitmap_offset = qemu_get_offset(file) + header_size;
> + block->pages_offset = ROUND_UP(block->bitmap_offset +
> + bitmap_size, 0x100000);
The 0x100000 gives us our 1 MB alignment.
This is quite an important thing, so can we put a nice clear
constant at the top of the file:
/* Align fixed-ram pages data to the next 1 MB boundary */
#define FIXED_RAM_PAGE_OFFSET_ALIGNMENT 0x100000
> @@ -3179,7 +3252,6 @@ out:
> qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> qemu_fflush(f);
> ram_transferred_add(8);
> -
> ret = qemu_file_get_error(f);
> }
> if (ret < 0) {
Supurious whitspace change, possibly better in whatever patch
introduced it, or dropped ?
With regards,
Daniel
--
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Daniel P. Berrangé <berrange@redhat.com> writes:
> On Mon, Oct 23, 2023 at 05:35:54PM -0300, Fabiano Rosas wrote:
>> From: Nikolay Borisov <nborisov@suse.com>
>>
>> Implement the outgoing migration side for the 'fixed-ram' capability.
>>
>> A bitmap is introduced to track which pages have been written in the
>> migration file. Pages are written at a fixed location for every
>> ramblock. Zero pages are ignored as they'd be zero in the destination
>> migration as well.
>>
>> The migration stream is altered to put the dirty pages for a ramblock
>> after its header instead of having a sequential stream of pages that
>> follow the ramblock headers. Since all pages have a fixed location,
>> RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration.
>>
>> Without fixed-ram (current):
>>
>> ramblock 1 header|ramblock 2 header|...|RAM_SAVE_FLAG_EOS|stream of
>> pages (iter 1)|RAM_SAVE_FLAG_EOS|stream of pages (iter 2)|...
>
> Clearer to diagram this vertically I think
>
> ---------------------
> | ramblock 1 header |
> ---------------------
> | ramblock 2 header |
> ---------------------
> | ... |
> ---------------------
> | ramblock n header |
> ---------------------
> | RAM_SAVE_FLAG_EOS |
> ---------------------
> | stream of pages |
> | (iter 1) |
> | ... |
> ---------------------
> | RAM_SAVE_FLAG_EOS |
> ---------------------
> | stream of pages |
> | (iter 2) |
> | ... |
> ---------------------
> | ... |
> ---------------------
>
>
>>
>> With fixed-ram (new):
>>
>> ramblock 1 header|ramblock 1 fixed-ram header|ramblock 1 pages (fixed
>> offsets)|ramblock 2 header|ramblock 2 fixed-ram header|ramblock 2
>> pages (fixed offsets)|...|RAM_SAVE_FLAG_EOS
>
> If I'm reading the code correctly the new format has some padding
> such that each "ramblock pages" region starts on a 1 MB boundary.
>
> eg so we get:
>
> --------------------------------
> | ramblock 1 header |
> --------------------------------
> | ramblock 1 fixed-ram header |
> --------------------------------
> | padding to next 1MB boundary |
> | ... |
> --------------------------------
> | ramblock 1 pages |
> | ... |
> --------------------------------
> | ramblock 2 header |
> --------------------------------
> | ramblock 2 fixed-ram header |
> --------------------------------
> | padding to next 1MB boundary |
> | ... |
> --------------------------------
> | ramblock 2 pages |
> | ... |
> --------------------------------
> | ... |
> --------------------------------
> | RAM_SAVE_FLAG_EOS |
> --------------------------------
> | ... |
> -------------------------------
>
>>
>> where:
>> - ramblock header: the generic information for a ramblock, such as
>> idstr, used_len, etc.
>>
>> - ramblock fixed-ram header: the new information added by this
>> feature: bitmap of pages written, bitmap size and offset of pages
>> in the migration file.
>>
>> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>> include/exec/ramblock.h | 8 ++++
>> migration/options.c | 3 --
>> migration/ram.c | 98 ++++++++++++++++++++++++++++++++++++-----
>> 3 files changed, 96 insertions(+), 13 deletions(-)
>>
>> diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
>> index 69c6a53902..e0e3f16852 100644
>> --- a/include/exec/ramblock.h
>> +++ b/include/exec/ramblock.h
>> @@ -44,6 +44,14 @@ struct RAMBlock {
>> size_t page_size;
>> /* dirty bitmap used during migration */
>> unsigned long *bmap;
>> + /* shadow dirty bitmap used when migrating to a file */
>> + unsigned long *shadow_bmap;
>> + /*
>> + * offset in the file pages belonging to this ramblock are saved,
>> + * used only during migration to a file.
>> + */
>> + off_t bitmap_offset;
>> + uint64_t pages_offset;
>> /* bitmap of already received pages in postcopy */
>> unsigned long *receivedmap;
>>
>> diff --git a/migration/options.c b/migration/options.c
>> index 2622d8c483..9f693d909f 100644
>> --- a/migration/options.c
>> +++ b/migration/options.c
>> @@ -271,12 +271,9 @@ bool migrate_events(void)
>>
>> bool migrate_fixed_ram(void)
>> {
>> -/*
>> MigrationState *s = migrate_get_current();
>>
>> return s->capabilities[MIGRATION_CAPABILITY_FIXED_RAM];
>> -*/
>> - return false;
>> }
>>
>> bool migrate_ignore_shared(void)
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 92769902bb..152a03604f 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -1157,12 +1157,18 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss,
>> return 0;
>> }
>>
>> + stat64_add(&mig_stats.zero_pages, 1);
>> +
>> + if (migrate_fixed_ram()) {
>> + /* zero pages are not transferred with fixed-ram */
>> + clear_bit(offset >> TARGET_PAGE_BITS, pss->block->shadow_bmap);
>> + return 1;
>> + }
>> +
>> len += save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLAG_ZERO);
>> qemu_put_byte(file, 0);
>> len += 1;
>> ram_release_page(pss->block->idstr, offset);
>> -
>> - stat64_add(&mig_stats.zero_pages, 1);
>> ram_transferred_add(len);
>>
>> /*
>> @@ -1220,14 +1226,20 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block,
>> {
>> QEMUFile *file = pss->pss_channel;
>>
>> - ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
>> - offset | RAM_SAVE_FLAG_PAGE));
>> - if (async) {
>> - qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
>> - migrate_release_ram() &&
>> - migration_in_postcopy());
>> + if (migrate_fixed_ram()) {
>> + qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE,
>> + block->pages_offset + offset);
>> + set_bit(offset >> TARGET_PAGE_BITS, block->shadow_bmap);
>> } else {
>> - qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
>> + ram_transferred_add(save_page_header(pss, pss->pss_channel, block,
>> + offset | RAM_SAVE_FLAG_PAGE));
>> + if (async) {
>> + qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE,
>> + migrate_release_ram() &&
>> + migration_in_postcopy());
>> + } else {
>> + qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
>> + }
>> }
>> ram_transferred_add(TARGET_PAGE_SIZE);
>> stat64_add(&mig_stats.normal_pages, 1);
>> @@ -2475,6 +2487,8 @@ static void ram_save_cleanup(void *opaque)
>> block->clear_bmap = NULL;
>> g_free(block->bmap);
>> block->bmap = NULL;
>> + g_free(block->shadow_bmap);
>> + block->shadow_bmap = NULL;
>> }
>>
>> xbzrle_cleanup();
>> @@ -2842,6 +2856,7 @@ static void ram_list_init_bitmaps(void)
>> */
>> block->bmap = bitmap_new(pages);
>> bitmap_set(block->bmap, 0, pages);
>> + block->shadow_bmap = bitmap_new(block->used_length >> TARGET_PAGE_BITS);
>> block->clear_bmap_shift = shift;
>> block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));
>> }
>> @@ -2979,6 +2994,44 @@ void qemu_guest_free_page_hint(void *addr, size_t len)
>> }
>> }
>>
>> +#define FIXED_RAM_HDR_VERSION 1
>> +struct FixedRamHeader {
>> + uint32_t version;
>> + uint64_t page_size;
>> + uint64_t bitmap_offset;
>> + uint64_t pages_offset;
>> + /* end of v1 */
>> +} QEMU_PACKED;
>> +
>> +static void fixed_ram_insert_header(QEMUFile *file, RAMBlock *block)
>> +{
>> + g_autofree struct FixedRamHeader *header;
>> + size_t header_size, bitmap_size;
>> + long num_pages;
>> +
>> + header = g_new0(struct FixedRamHeader, 1);
>> + header_size = sizeof(struct FixedRamHeader);
>> +
>> + num_pages = block->used_length >> TARGET_PAGE_BITS;
>> + bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long);
>> +
>> + /*
>> + * Save the file offsets of where the bitmap and the pages should
>> + * go as they are written at the end of migration and during the
>> + * iterative phase, respectively.
>> + */
>> + block->bitmap_offset = qemu_get_offset(file) + header_size;
>> + block->pages_offset = ROUND_UP(block->bitmap_offset +
>> + bitmap_size, 0x100000);
>
> The 0x100000 gives us our 1 MB alignment.
>
> This is quite an important thing, so can we put a nice clear
> constant at the top of the file:
>
> /* Align fixed-ram pages data to the next 1 MB boundary */
> #define FIXED_RAM_PAGE_OFFSET_ALIGNMENT 0x100000
>
>> @@ -3179,7 +3252,6 @@ out:
>> qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>> qemu_fflush(f);
>> ram_transferred_add(8);
>> -
>> ret = qemu_file_get_error(f);
>> }
>> if (ret < 0) {
>
> Supurious whitspace change, possibly better in whatever patch
> introduced it, or dropped ?
>
>
> With regards,
> Daniel
I'll apply all the suggestions. Thanks!
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