[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 1/4] multifd: Change page count default to 128
From: |
Daniel P . Berrangé |
Subject: |
Re: [Qemu-devel] [PATCH 1/4] multifd: Change page count default to 128 |
Date: |
Thu, 7 Feb 2019 11:33:12 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Wed, Feb 06, 2019 at 02:23:28PM +0100, Juan Quintela wrote:
> I haven't seend any problem about using 64 or 128. And it make much
> less contention on the locks. Just change it.
Isn't there a issue with having a fixed page count given the
very different default page sizes across architectures ?
x86 is 4kb pages, while ppc64 uses 64kb pages IIUC.
This would mean current value of 64 pages, would correspond
to 1/4 MB on x86, and 4 MB on ppc64. The new value would
be 1/2 MB on x86 and 8 MB on ppc64.
Should we instead be measuring this tunable in units that
are independant of page size ? eg meansure in KB, with a
requirement that the value is a multiple of the page size.
Then set the default to 512 KB ?
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> migration/migration.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index ef1d53cde2..f673486679 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -81,7 +81,7 @@
> /* The delay time (in ms) between two COLO checkpoints */
> #define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY (200 * 100)
> #define DEFAULT_MIGRATE_MULTIFD_CHANNELS 2
> -#define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 16
> +#define DEFAULT_MIGRATE_MULTIFD_PAGE_COUNT 128
>
> /* Background transfer rate for postcopy, 0 means unlimited, note
> * that page requests can still exceed this limit.
> --
> 2.20.1
>
>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
Re: [Qemu-devel] [PATCH 2/4] multifd: Drop x-multifd-page-count parameter, Daniel P . Berrangé, 2019/02/07