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Re: [Qemu-devel] [PATCH v2 5/8] multifd: Be flexible about packet size
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/8] multifd: Be flexible about packet size |
Date: |
Thu, 21 Feb 2019 18:30:21 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
* Juan Quintela (address@hidden) wrote:
> This way we can change the packet size in the future and everything
> will work. We choose an arbitrary big number (100 times configured
> size) as a limit about how big we will reallocate.
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> migration/ram.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index e22d02760b..75a8fc21f8 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -723,13 +723,13 @@ static void multifd_pages_clear(MultiFDPages_t *pages)
> static void multifd_send_fill_packet(MultiFDSendParams *p)
> {
> MultiFDPacket_t *packet = p->packet;
> - uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
> + uint32_t page_max = MULTIFD_PACKET_SIZE / qemu_target_page_size();
> int i;
>
> packet->magic = cpu_to_be32(MULTIFD_MAGIC);
> packet->version = cpu_to_be32(MULTIFD_VERSION);
> packet->flags = cpu_to_be32(p->flags);
> - packet->pages_alloc = cpu_to_be32(page_count);
> + packet->pages_alloc = cpu_to_be32(page_max);
> packet->pages_used = cpu_to_be32(p->pages->used);
> packet->next_packet_size = cpu_to_be32(p->next_packet_size);
> packet->packet_num = cpu_to_be64(p->packet_num);
> @@ -746,7 +746,7 @@ static void multifd_send_fill_packet(MultiFDSendParams *p)
> static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
> {
> MultiFDPacket_t *packet = p->packet;
> - uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size();
> + uint32_t pages_max = MULTIFD_PACKET_SIZE / qemu_target_page_size();
> RAMBlock *block;
> int i;
>
> @@ -769,12 +769,24 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams
> *p, Error **errp)
> p->flags = be32_to_cpu(packet->flags);
>
> packet->pages_alloc = be32_to_cpu(packet->pages_alloc);
> - if (packet->pages_alloc > page_count) {
> + /*
> + * If we recevied a packet that is 100 times bigger than expected
> + * just stop migration. It is a magic number.
> + */
> + if (packet->pages_alloc > pages_max * 100) {
> error_setg(errp, "multifd: received packet "
> - "with size %d and expected maximum size %d",
> - packet->pages_alloc, page_count) ;
> + "with size %d and expected size %d",
> + packet->pages_alloc, pages_max) ;
Should that end with pages_max * 100 ?
> return -1;
> }
> + /*
> + * We received a packet that is bigger than expected but inside
> + * reasonable limits (see previous comment). Just reallocate.
> + */
> + if (packet->pages_alloc > p->pages->allocated) {
> + multifd_pages_clear(p->pages);
> + multifd_pages_init(packet->pages_alloc);
> + }
>
> p->pages->used = be32_to_cpu(packet->pages_used);
> if (p->pages->used > packet->pages_alloc) {
Other than that error message, I think it's OK, although the names get
very confusing (max, alloc, allocated)
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> --
> 2.20.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH v2 1/8] multifd: Only send pages when packet are not empty, (continued)
- [Qemu-devel] [PATCH v2 3/8] multifd: Create new next_packet_size field, Juan Quintela, 2019/02/20
- [Qemu-devel] [PATCH v2 2/8] multifd: Rename "size" member to pages_alloc, Juan Quintela, 2019/02/20
- [Qemu-devel] [PATCH v2 4/8] multifd: Drop x-multifd-page-count parameter, Juan Quintela, 2019/02/20
- [Qemu-devel] [PATCH v2 8/8] tests: Add migration multifd test, Juan Quintela, 2019/02/20
- [Qemu-devel] [PATCH v2 5/8] multifd: Be flexible about packet size, Juan Quintela, 2019/02/20
- Re: [Qemu-devel] [PATCH v2 5/8] multifd: Be flexible about packet size,
Dr. David Alan Gilbert <=
- [Qemu-devel] [PATCH v2 7/8] multifd: Drop x-, Juan Quintela, 2019/02/20
- [Qemu-devel] [PATCH v2 6/8] multifd: Change default packet size, Juan Quintela, 2019/02/20