On Wed, Jun 07, 2017 at 12:46:34PM +0300, Alexey Perevalov wrote:
> This patch adds ability to track down already copied
> pages, it's necessary for calculation vCPU block time in
> postcopy migration feature, maybe for restore after
> postcopy migration failure.
> Also it's necessary to solve shared memory issue in
> postcopy livemigration. Information about copied pages
> will be transferred to the software virtual bridge
> (e.g. OVS-VSWITCHD), to avoid fallocate (unmap) for
> already copied pages. fallocate syscall is required for
> remmaped shared memory, due to remmaping itself blocks
> ioctl(UFFDIO_COPY, ioctl in this case will end with EEXIT
> error (struct page is exists after remmap).
>
> Bitmap is placed into RAMBlock as another postcopy/precopy
> related bitmaps. Helpers are in migration/ram.c, due to
> in this file is allowing to work with RAMBlock.
>
> Signed-off-by: Alexey Perevalov <a.pereva...@samsung.com>
Hi, Alexey,
Besides all the existing comments, I would suggest you do all the
copied_map things in this single patch, so that it'll be easier for
others to work upon your work. E.g., move the bit_set() operations
here as well (currently it was in followup patches, and looks like
that's not enough since we need to capture copied_map even for precopy
phase), then this single patch can ideally be separated from the whole
series (and then I can work upon it :-).
Or, please just let me know if you want me to do this for you. I can
post this as a standalone patch, with your s-o-b if you allow.
Thanks,
> ---
> include/exec/ram_addr.h | 2 ++
> migration/ram.c | 36 ++++++++++++++++++++++++++++++++++++
> migration/ram.h | 4 ++++
> 3 files changed, 42 insertions(+)
>
> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> index 140efa8..6a3780b 100644
> --- a/include/exec/ram_addr.h
> +++ b/include/exec/ram_addr.h
> @@ -47,6 +47,8 @@ struct RAMBlock {
> * of the postcopy phase
> */
> unsigned long *unsentmap;
> + /* bitmap of already copied pages in postcopy */
> + unsigned long *copiedmap;
> };
>
> static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset)
> diff --git a/migration/ram.c b/migration/ram.c
> index f387e9c..a7c0db4 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -149,6 +149,25 @@ out:
> return ret;
> }
>
> +static unsigned long int get_copied_bit_offset(uint64_t addr, RAMBlock *rb)
> +{
> + uint64_t addr_offset = addr - (uint64_t)(uintptr_t)rb->host;
> + int page_shift = find_first_bit((unsigned long *)&rb->page_size,
> + sizeof(rb->page_size));
> +
> + return addr_offset >> page_shift;
> +}
> +
> +int test_copiedmap_by_addr(uint64_t addr, RAMBlock *rb)
> +{
> + return test_bit(get_copied_bit_offset(addr, rb), rb->copiedmap);
> +}
> +
> +void set_copiedmap_by_addr(uint64_t addr, RAMBlock *rb)
> +{
> + set_bit_atomic(get_copied_bit_offset(addr, rb), rb->copiedmap);
> +}
> +
> /*
> * An outstanding page request, on the source, having been received
> * and queued
> @@ -1449,6 +1468,8 @@ static void ram_migration_cleanup(void *opaque)
> block->bmap = NULL;
> g_free(block->unsentmap);
> block->unsentmap = NULL;
> + g_free(block->copiedmap);
> + block->copiedmap = NULL;
> }
>
> XBZRLE_cache_lock();
> @@ -2517,6 +2538,14 @@ static int ram_load_postcopy(QEMUFile *f)
> return ret;
> }
>
> +static unsigned long get_copiedmap_size(RAMBlock *rb)
> +{
> + unsigned long pages;
> + pages = rb->max_length >> find_first_bit((unsigned long *)&rb->page_size,
> + sizeof(rb->page_size));
> + return pages;
> +}
> +
> static int ram_load(QEMUFile *f, void *opaque, int version_id)
> {
> int flags = 0, ret = 0;
> @@ -2544,6 +2573,13 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> rcu_read_lock();
>
> if (postcopy_running) {
> + RAMBlock *rb;
> + RAMBLOCK_FOREACH(rb) {
> + /* need for destination, bitmap_new calls
> + * g_try_malloc0 and this function
> + * Attempts to allocate @n_bytes, initialized to 0'sh */
> + rb->copiedmap = bitmap_new(get_copiedmap_size(rb));
> + }
> ret = ram_load_postcopy(f);
> }
>
> diff --git a/migration/ram.h b/migration/ram.h
> index c9563d1..1f32824 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -67,4 +67,8 @@ int ram_discard_range(const char *block_name, uint64_t
> start, size_t length);
> int ram_postcopy_incoming_init(MigrationIncomingState *mis);
>
> void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
> +
> +int test_copiedmap_by_addr(uint64_t addr, RAMBlock *rb);
> +void set_copiedmap_by_addr(uint64_t addr, RAMBlock *rb);
> +
> #endif
> --
> 1.9.1
>
--
Peter Xu
