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Re: [Qemu-devel] [PATCH for-2.10 06/10] hmp: Clean up and simplify hmp_m
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH for-2.10 06/10] hmp: Clean up and simplify hmp_migrate_set_parameter() |
Date: |
Tue, 18 Jul 2017 12:34:49 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 |
On 07/18/2017 08:41 AM, Markus Armbruster wrote:
> The bulk of hmp_migrate_set_parameter()'s code sets one member of
> MigrationParameters according to the command's arguments. It uses a
> string visitor for integer and boolean members, but not for string and
> size members. It calls visit_type_bool() right away, but delays
> visit_type_int() some. The delaying requires a flag variable and a
> bit of trickery: we set all integer members instead of just the one we
> want, and rely on the has_FOOs to mask the unwanted ones.
>
> Clean this up as follows. Don't delay calling visit_type_int(). Use
> the string visitor for strings, too. This involves extra allocations
> and cleanup, but doing them is simpler and cleaner than avoiding them.
>
> Sadly, using the string visitor for sizes isn't possible, because it
> defaults to Bytes rather than Mebibytes. Add a comment explaining
> that.
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
> hmp.c | 78
> ++++++++++++++++++++++++++++---------------------------------------
> 1 file changed, 32 insertions(+), 46 deletions(-)
>
Diffstat says it's cleaner.
> case MIGRATION_PARAMETER_MAX_BANDWIDTH:
> - p.has_max_bandwidth = true;
> + p->has_max_bandwidth = true;
> + /*
> + * Can't use visit_type_size() here, because it
> + * defaults to Bytes rather than Mebibytes.
> + */
> ret = qemu_strtosz_MiB(valuestr, NULL, &valuebw);
Can we munge valuestr (if it has a suffix, leave it alone; if it has
none, tack on "M"), and then call the size visitor as usual?
> if (ret < 0 || valuebw > INT64_MAX
> || (size_t)valuebw != valuebw) {
> error_setg(&err, "Invalid size %s", valuestr);
> - goto cleanup;
> + break;
> }
But for now, the inline version works.
> - /* Set all integers; only one has_FOO will be set, and
> - * the code ignores the remaining values */
> - p.compress_level = valueint;
> - p.compress_threads = valueint;
> - p.decompress_threads = valueint;
> - p.cpu_throttle_initial = valueint;
> - p.cpu_throttle_increment = valueint;
> - p.downtime_limit = valueint;
> - p.x_checkpoint_delay = valueint;
> + if (err) {
> + goto cleanup;
> }
>
> - qmp_migrate_set_parameters(&p, &err);
The old code is calling qmp_migrate_set_parameters() once per loop
iteration, because it could only parse one integer per loop.
> + qmp_migrate_set_parameters(p, &err);
But couldn't you now sink this below the loop, and call it only once
after all members are parsed? Can be a separate patch, though.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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