Re: [PATCH] multifd: Add colo support

[Lukas Straub <lukasstraub2@web.de>]

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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.

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



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