On Mon, Jun 26, 2017 at 11:35:20AM +0300, Alexey Perevalov wrote:
> This patch adds ability to track down already received
> 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 received pages
> will be transferred to the software virtual bridge
> (e.g. OVS-VSWITCHD), to avoid fallocate (unmap) for
> already received 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.
>
> Signed-off-by: Alexey Perevalov <a.pereva...@samsung.com>
Mostly good to me, some minor nits only...
[...]
> static int qemu_ufd_copy_ioctl(int userfault_fd, void *host_addr,
> - void *from_addr, uint64_t pagesize)
> + void *from_addr, uint64_t pagesize, RAMBlock
> *rb)
> {
> + int ret;
> if (from_addr) {
> struct uffdio_copy copy_struct;
> copy_struct.dst = (uint64_t)(uintptr_t)host_addr;
> copy_struct.src = (uint64_t)(uintptr_t)from_addr;
> copy_struct.len = pagesize;
> copy_struct.mode = 0;
> - return ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
> + ret = ioctl(userfault_fd, UFFDIO_COPY, ©_struct);
> } else {
> struct uffdio_zeropage zero_struct;
> zero_struct.range.start = (uint64_t)(uintptr_t)host_addr;
> zero_struct.range.len = pagesize;
> zero_struct.mode = 0;
> - return ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
> + ret = ioctl(userfault_fd, UFFDIO_ZEROPAGE, &zero_struct);
> + }
> + /* received page isn't feature of blocktime calculation,
> + * it's more general entity, so keep it here,
> + * but gup betwean two following operation could be high,
> + * and in this case blocktime for such small interval will be lost */
I would drop this comment for this patch. It didn't help me to be
clearer on the code but a bit more messy... Maybe it suites for some
place in the blocktime series? Not sure.
[...]
> +void ramblock_recv_map_init(void)
> +{
> + RAMBlock *rb;
> +
> + RAMBLOCK_FOREACH(rb) {
> + unsigned long pages;
> + pages = rb->max_length >> TARGET_PAGE_BITS;
> + assert(!rb->receivedmap);
> + rb->receivedmap = bitmap_new(pages);
I'll prefer removing pages variable since used only once.
[...]
> +static void ramblock_recv_bitmap_clear_range(uint64_t start, size_t length,
> + RAMBlock *rb)
> +{
> + int i, range_count;
> + long nr_bit = start >> TARGET_PAGE_BITS;
> + range_count = length >> TARGET_PAGE_BITS;
> + for (i = 0; i < range_count; i++) {
> + clear_bit(nr_bit, rb->receivedmap);
> + nr_bit += 1;
(Dave commented this one)
[...]
> @@ -2513,6 +2560,7 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> ram_addr_t addr, total_ram_bytes;
> void *host = NULL;
> uint8_t ch;
> + RAMBlock *rb = NULL;
>
> addr = qemu_get_be64(f);
> flags = addr & ~TARGET_PAGE_MASK;
> @@ -2520,15 +2568,15 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
>
> if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
> RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
> - RAMBlock *block = ram_block_from_stream(f, flags);
> + rb = ram_block_from_stream(f, flags);
>
> - host = host_from_ram_block_offset(block, addr);
> + host = host_from_ram_block_offset(rb, addr);
> if (!host) {
> error_report("Illegal RAM offset " RAM_ADDR_FMT, addr);
> ret = -EINVAL;
> break;
> }
IMHO it's ok to set the bit once here. Thanks,
> - trace_ram_load_loop(block->idstr, (uint64_t)addr, flags, host);
> + trace_ram_load_loop(rb->idstr, (uint64_t)addr, flags, host);
> }
>
> switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
> @@ -2582,10 +2630,12 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
>
> case RAM_SAVE_FLAG_ZERO:
> ch = qemu_get_byte(f);
> + ramblock_recv_bitmap_set(host, rb);
> ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
> break;
>
> case RAM_SAVE_FLAG_PAGE:
> + ramblock_recv_bitmap_set(host, rb);
> qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
> break;
>
> @@ -2596,10 +2646,13 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> ret = -EINVAL;
> break;
> }
> +
> + ramblock_recv_bitmap_set(host, rb);
> decompress_data_with_multi_threads(f, host, len);
> break;
>
> case RAM_SAVE_FLAG_XBZRLE:
> + ramblock_recv_bitmap_set(host, rb);
> if (load_xbzrle(f, addr, host) < 0) {
> error_report("Failed to decompress XBZRLE page at "
> RAM_ADDR_FMT, addr);
--
Peter Xu
