On 06/21/2010 12:31 PM, Zhang, Yanmin wrote:
The 2nd patch is to change the definition of perf_event to facilitate
perf attr copy when a hypercall happens.
Signed-off-by: Zhang Yanmin<yanmin_zhang@xxxxxxxxxxxxxxx>
---
--- linux-2.6_tip0620/include/linux/perf_event.h 2010-06-21 15:19:52.821999849 +0800
+++ linux-2.6_tip0620perfkvm/include/linux/perf_event.h 2010-06-21 16:53:49.283999849 +0800
@@ -188,7 +188,10 @@ struct perf_event_attr {
__u64 sample_type;
__u64 read_format;
Assuming these flags are available to the guest?
- __u64 disabled : 1, /* off by default */
+ union {
+ __u64 flags;
+ struct {
+ __u64 disabled : 1, /* off by default */
inherit : 1, /* children inherit it */
inherit is meaningless for a guest.
pinned : 1, /* must always be on PMU */
We cannot allow a guest to pin a counter.
The other flags are also problematic. I'd like to see virt-specific
flags (probably we'll only need kernel/user and nested_hv for nested
virtualization).
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?
+ /*
+ * 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.
@@ -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. This would reduce the number of exits. Also adjust the
frequency less frequently.
+
+ if (adjust_freq) {
+ perf_ctx_adjust_freq(&cpuctx->ctx);
+ if (ctx)
+ perf_ctx_adjust_freq(ctx);
+ }
--
error compiling committee.c: too many arguments to function
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