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Re: [PATCH v3 21/23] multifd: Support for zero pages transmission
From: |
Juan Quintela |
Subject: |
Re: [PATCH v3 21/23] multifd: Support for zero pages transmission |
Date: |
Thu, 02 Dec 2021 17:19:10 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> * Juan Quintela (quintela@redhat.com) wrote:
>> "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
>> > * Juan Quintela (quintela@redhat.com) wrote:
>> >> This patch adds counters and similar. Logic will be added on the
>> >> following patch.
>> >>
>> >> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> >> ---
>> >> migration/multifd.h | 13 ++++++++++++-
>> >> migration/multifd.c | 22 +++++++++++++++++++---
>> >> migration/trace-events | 2 +-
>> >> 3 files changed, 32 insertions(+), 5 deletions(-)
>> >>
>> >> diff --git a/migration/multifd.h b/migration/multifd.h
>> >> index 39e55d7f05..973315b545 100644
>> >> --- a/migration/multifd.h
>> >> +++ b/migration/multifd.h
>> >> @@ -49,7 +49,10 @@ typedef struct {
>> >> /* size of the next packet that contains pages */
>> >> uint32_t next_packet_size;
>> >> uint64_t packet_num;
>> >> - uint64_t unused[4]; /* Reserved for future use */
>> >> + /* zero pages */
>> >> + uint32_t zero_pages;
>> >
>> > Had you considered just adding a flag, MULTIFD_FLAG_ZERO to the packet?
>>
>> I *have* to also add the flag.
>
> I meant can't you add a flag to say that this whole packet is zero pages
> and then you only need one counter.
No, in general packets are going to transmit *both*, zero pages and
normal pages. It depends on the content that one receives.
Later, Juan.
> Dave
>
>> I was waiting for 7.0 to get out, because I still have to do the
>> compatibility bits. Otherwise you can't migrate to an old multifd version.
>>
>> >
>> >> + uint32_t unused32[1]; /* Reserved for future use */
>> >> + uint64_t unused64[3]; /* Reserved for future use */
>> >> char ramblock[256];
>> >> uint64_t offset[];
>> >> } __attribute__((packed)) MultiFDPacket_t;
>> >> @@ -117,6 +120,10 @@ typedef struct {
>> >> ram_addr_t *normal;
>> >> /* num of non zero pages */
>> >> uint32_t normal_num;
>> >> + /* Pages that are zero */
>> >> + ram_addr_t *zero;
>> >> + /* num of zero pages */
>> >> + uint32_t zero_num;
>> >> /* used for compression methods */
>> >> void *data;
>> >> } MultiFDSendParams;
>> >> @@ -162,6 +169,10 @@ typedef struct {
>> >> ram_addr_t *normal;
>> >> /* num of non zero pages */
>> >> uint32_t normal_num;
>> >> + /* Pages that are zero */
>> >> + ram_addr_t *zero;
>> >> + /* num of zero pages */
>> >> + uint32_t zero_num;
>> >> /* used for de-compression methods */
>> >> void *data;
>> >> } MultiFDRecvParams;
>> >> diff --git a/migration/multifd.c b/migration/multifd.c
>> >> index d1ab823f98..2e4dffd6c6 100644
>> >> --- a/migration/multifd.c
>> >> +++ b/migration/multifd.c
>> >> @@ -265,6 +265,7 @@ static void
>> >> multifd_send_fill_packet(MultiFDSendParams *p)
>> >> packet->normal_pages = cpu_to_be32(p->normal_num);
>> >> packet->next_packet_size = cpu_to_be32(p->next_packet_size);
>> >> packet->packet_num = cpu_to_be64(p->packet_num);
>> >> + packet->zero_pages = cpu_to_be32(p->zero_num);
>> >>
>> >> if (p->pages->block) {
>> >> strncpy(packet->ramblock, p->pages->block->idstr, 256);
>> >> @@ -327,7 +328,15 @@ static int
>> >> multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
>> >> p->next_packet_size = be32_to_cpu(packet->next_packet_size);
>> >> p->packet_num = be64_to_cpu(packet->packet_num);
>> >>
>> >> - if (p->normal_num == 0) {
>> >> + p->zero_num = be32_to_cpu(packet->zero_pages);
>> >> + if (p->zero_num > packet->pages_alloc - p->normal_num) {
>> >> + error_setg(errp, "multifd: received packet "
>> >> + "with %d zero pages and expected maximum pages are
>> >> %d",
>> >> + p->normal_num, packet->pages_alloc - p->zero_num) ;
>> >
>> > should that be p->zero_num, packet->pages_alloc - p->normal_num ?
>> > (and be %u)
>>
>> Copy and paste error. You are right on both cases.
>>
>> Thanks.
>>