Re: [PATCH] multifd: Add colo support

[Juan Quintela <quintela@redhat.com>]

Lukas Straub <lukasstraub2@web.de> wrote:
> On Tue,  9 May 2023 20:15:28 +0200
> Juan Quintela <quintela@redhat.com> wrote:
>
>> From: Lukas Straub <lukasstraub2@web.de>
>> 
>> Like in the normal ram_load() path, put the received pages into the
>> colo cache and mark the pages in the bitmap so that they will be
>> flushed to the guest later.
>> 
>> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
>> 
>> ---
>> 
>> Hi Lukas
>> 
>> What about this instead of your other three patches?  I think it is
>> clearer, and I don't think that we are going to have anything else
>> that is going to hook there anytime soon.
>> 
>> Notice that I put CONFIG_COLO waiting for Vladimir changes to get in
>> before I merge this.
>> 
>> Notice also that I "lost" the line:
>> 
>>   p->host = p->block->host;
>> 
>> In the error case.  But in that case we are aborting the migration, so
>> we don't care.
>> 
>> Can you check if it works for you?
>> Here it compiles, so it must be perfect.
>> 
>> Thanks, Juan.
>
> This way is okay for now. Though I will send a patch.


If it works for you, you can add a review-by and I will integrate in
next PULL.

Later, Juan.

>
> Regards,
> Lukas Straub
>
>> ---
>>  migration/meson.build    |  2 +-
>>  migration/multifd-colo.c | 49 ++++++++++++++++++++++++++++++++++++++++
>>  migration/multifd-colo.h | 24 ++++++++++++++++++++
>>  3 files changed, 74 insertions(+), 1 deletion(-)
>>  create mode 100644 migration/multifd-colo.c
>>  create mode 100644 migration/multifd-colo.h
>> 
>> diff --git a/migration/meson.build b/migration/meson.build
>> index 75de868bb7..c9db40d4d4 100644
>> --- a/migration/meson.build
>> +++ b/migration/meson.build
>> @@ -23,7 +23,7 @@ softmmu_ss.add(files(
>>    'migration.c',
>>    'multifd.c',
>>    'multifd-zlib.c',
>> -  'multifd-zlib.c',
>> +  'multifd-colo.c',
>>    'ram-compress.c',
>>    'options.c',
>>    'postcopy-ram.c',
>> diff --git a/migration/multifd-colo.c b/migration/multifd-colo.c
>> new file mode 100644
>> index 0000000000..10fa1467fa
>> --- /dev/null
>> +++ b/migration/multifd-colo.c
>> @@ -0,0 +1,49 @@
>> +/*
>> + * multifd colo implementation
>> + *
>> + * Copyright (c) Lukas Straub <lukasstraub2@web.de>
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "exec/target_page.h"
>> +#include "exec/ramblock.h"
>> +#include "qemu/error-report.h"
>> +#include "qapi/error.h"
>> +#include "ram.h"
>> +#include "multifd.h"
>> +#include "options.h"
>> +#include "io/channel-socket.h"
>> +#include "migration/colo.h"
>> +#include "multifd-colo.h"
>> +
>> +void multifd_colo_prepare_recv_pages(MultiFDRecvParams *p)
>> +{
>> +    if (migrate_colo()) {
>> +        /*
>> +         * While we're still in precopy mode, we copy received pages to both guest
>> +         * and cache. No need to set dirty bits, since guest and cache memory are
>> +         * in sync.
>> +         */
>> +        if (migration_incoming_in_colo_state()) {
>> +            colo_record_bitmap(p->block, p->normal, p->normal_num);
>> +        }
>> +        p->host = p->block->colo_cache;
>> +    }
>> +}
>> +
>> +void multifd_colo_process_recv_pages(MultiFDRecvParams *p)
>> +{
>> +    if (migrate_colo()) {
>> +        if (!migration_incoming_in_colo_state()) {
>> +            for (int i = 0; i < p->normal_num; i++) {
>> +                void *guest = p->block->host + p->normal[i];
>> +                void *cache = p->host + p->normal[i];
>> +                memcpy(guest, cache, p->page_size);
>> +            }
>> +        }
>> +        p->host = p->block->host;
>> +    }
>> +}
>> diff --git a/migration/multifd-colo.h b/migration/multifd-colo.h
>> new file mode 100644
>> index 0000000000..1636c617fc
>> --- /dev/null
>> +++ b/migration/multifd-colo.h
>> @@ -0,0 +1,24 @@
>> +/*
>> + * multifd colo header
>> + *
>> + * Copyright (c) Lukas Straub <lukasstraub2@web.de>
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + */
>> +
>> +#ifndef QEMU_MIGRATION_MULTIFD_COLO_H
>> +#define QEMU_MIGRATION_MULTIFD_COLO_H
>> +
>> +#ifndef CONFIG_COLO
>> +
>> +void multifd_colo_prepare_recv_pages(MultiFDRecvParams *p);
>> +void multifd_colo_process_recv_pages(MultiFDRecvParams *p);
>> +
>> +#else
>> +
>> +static inline void multifd_colo_prepare_recv_pages(MultiFDRecvParams *p) {}
>> +static inline void multifd_colo_process_recv_pages(MultiFDRecvParams *p) {}
>> +
>> +#endif /* CONFIG_COLO */
>> +#endif