-----Original Message----- From: Jiri Denemark [mailto:jdenemar@redhat.com] Sent: Tuesday, November 24, 2015 12:25 AM To: Ren, Qiaowei Cc: libvir-list@redhat.com Subject: Re: [libvirt] [PATCH 3/8] perf: implement the public APIs for perf event
On Tue, Nov 17, 2015 at 16:00:43 +0800, Qiaowei Ren wrote:
* src/libvirt-domain.c: Implement virDomainGetPerfEvents and virDomainSetPerfEvents.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com> --- src/libvirt-domain.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 106 insertions(+)
diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index de7eb04..e767606 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -9572,6 +9572,112 @@ virDomainOpenChannel(virDomainPtr dom,
/** + * virDomainGetPerfEvents: + * @domain: pointer to domain object + * @params: pointer to perf events parameter object + * (return value, allocated by the caller) + * @nparams: pointer to number of perf event parameters + * + * Get all perf events setting. On input, @nparams gives the size of + the + * @params array; on output, @nparams gives how many slots were + filled + * with parameter information, which might be less but will not + exceed + * the input value. + * + * As a special case, calling with @params as NULL and @nparams as 0 + on + * input will cause @nparams on output to contain the number of + parameters + * supported by the hypervisor. The caller should then allocate + @params + * array, i.e. (sizeof(@virTypedParameter) * @nparams) bytes and call + the + * API again. + * + * See virDomainGetMemoryParameters() for an equivalent usage example.
You took a wrong API to copy. Requiring the caller to run the API with @params == NULL to get the number of parameters and then pass the allocated @params to get the values is the original design which we do not use for new APIs. The API should just allocate @params, fill it with all the values it knows about, and return the count in @nparams. In other words, no caller allocated arrays, please. You can look at, e.g., virDomainGetJobStats to see how it works.
Thanks, Jirka. I will update this patch according to new API design. Thanks, Qiaowei