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Re: [PATCH v5 02/10] kvm: Support for querying fd-based stats
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v5 02/10] kvm: Support for querying fd-based stats |
Date: |
Wed, 8 Jun 2022 17:01:44 +0100 |
User-agent: |
Mutt/2.2.1 (2022-02-19) |
* Paolo Bonzini (pbonzini@redhat.com) wrote:
> On 6/8/22 16:52, Dr. David Alan Gilbert wrote:
> > > If you mean why not some other source, each source has a different file
> > > descriptor:
> > >
> > > + int stats_fd = kvm_vcpu_ioctl(cpu, KVM_GET_STATS_FD, NULL);
> > >
> > > but the descriptors are consistent every time KVM_GET_STATS_FD is called,
> > > so
> > > basically "ident" can be used as a cache key.
> >
> > Ah OK, this is what I was after; it's a little weird that the caller
> > does the ioctl to get the stats-fd, but it does the lookup internally
> > with current_cpu for the ident.
>
> Oh yeah that's weird.
>
> Let me squash in this:
Yeh that's nicer; a comment something like:
'Find descriptors for 'target', either that have already been read or
query 'stats_fd' to read them from kvm'
?
Dave
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 023bf4ea79..71896ad173 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -3871,17 +3871,7 @@ static StatsDescriptors
> *find_stats_descriptors(StatsTarget target, int stats_fd
> size_t size_desc;
> ssize_t ret;
> - switch (target) {
> - case STATS_TARGET_VM:
> - ident = StatsTarget_str(STATS_TARGET_VM);
> - break;
> - case STATS_TARGET_VCPU:
> - ident = current_cpu->parent_obj.canonical_path;
> - break;
> - default:
> - abort();
> - }
> -
> + ident = StatsTarget_str(target);
> QTAILQ_FOREACH(descriptors, &stats_descriptors, next) {
> if (g_str_equal(descriptors->ident, ident)) {
> return descriptors;
> @@ -3917,7 +3907,7 @@ static StatsDescriptors
> *find_stats_descriptors(StatsTarget target, int stats_fd
> }
> descriptors->kvm_stats_header = kvm_stats_header;
> descriptors->kvm_stats_desc = kvm_stats_desc;
> - descriptors->ident = g_strdup(ident);
> + descriptors->ident = ident;
> QTAILQ_INSERT_TAIL(&stats_descriptors, descriptors, next);
> return descriptors;
> }
>
> (once I test it).
>
> Paolo
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK