On 06/22/2010 05:08 AM, Zhang, Yanmin wrote:
Something that is worrying is that we don't expose group information.
perf will multiplex the events for us, but there will be a loss in accuracy.
#ifdef CONFIG_HAVE_HW_BREAKPOINT
#include<asm/hw_breakpoint.h>
#endif
@@ -753,6 +752,20 @@ struct perf_event {
perf_overflow_handler_t overflow_handler;
+ /*
+ * pointers used by kvm perf paravirt interface.
+ *
+ * 1) Used in host kernel and points to host_perf_shadow which
+ * has information about guest perf_event
+ */
+ void *host_perf_shadow;
Can we have real types instead of void pointers?
I just want perf generic codes have less dependency on KVM codes.
One way to do that and retain type safety is to have
struct perf_client {
struct perf_client_ops *ops;
...
}
The client (kvm) can do
struct kvm_perf_client {
struct perf_client pc;
// kvm specific stuff
};
the callbacks receive struct perf_client and use container_of to reach
the kvm_perf_client that contains it.
+ /*
+ * 2) Used in guest kernel and points to guest_perf_shadow which
+ * is used as a communication area with host kernel. Host kernel
+ * copies overflow data to it when an event overflows.
+ */
+ void *guest_perf_shadow;
It's strange to see both guest and host parts in the same patch.
Splitting to separate patches will really help review.
It's a little hard to split the patches if they change the same file. Perhaps
I could add more statements before the patch when I send it out.
With git, it's easy (once you're used to it):
# go back one commit:
git reset HEAD^
# selectively add bits:
git add -p
# commit first patch
git commit -s
# selectively add bits:
git add -p
# commit second patch
git commit -s
@@ -1626,9 +1629,22 @@ void perf_event_task_tick(struct task_st
if (ctx&& ctx->nr_events&& ctx->nr_events != ctx->nr_active)
rotate = 1;
- perf_ctx_adjust_freq(&cpuctx->ctx);
- if (ctx)
- perf_ctx_adjust_freq(ctx);
+#ifdef CONFIG_KVM_PERF
+ if (kvm_para_available()) {
+ /*
+ * perf_ctx_adjust_freq causes lots of pmu->read which would
+ * trigger too many vmexit to host kernel. We disable it
+ * under para virt situation
+ */
+ adjust_freq = 0;
+ }
+#endif
Perhaps we can have a batch read interface which will read many counters
at once.
It's a good idea. But that will touch many perf generic codes which causes it's
hard
to maintain or follow future changes.
I'm talking about the guest/host interface. So you have one vmexit and
many host perf calls.
--
error compiling committee.c: too many arguments to function
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