[RFC kvm-unit-tests] api: Add dirty logging performance test

[Takuya Yoshikawa <takuya.yoshikawa@gmail.com>]

Check how long it takes to get dirty log according to the number of
dirty pages, like:

  get dirty log:     49 us for          1 dirty pages
  get dirty log:     49 us for          2 dirty pages
  get dirty log:     45 us for          4 dirty pages
  get dirty log:     41 us for          8 dirty pages
  get dirty log:     40 us for         16 dirty pages
  get dirty log:     44 us for         32 dirty pages
  get dirty log:     39 us for         64 dirty pages
  get dirty log:     42 us for        128 dirty pages
  get dirty log:     45 us for        256 dirty pages
  get dirty log:     53 us for        512 dirty pages
  get dirty log:     72 us for       1024 dirty pages
  get dirty log:     99 us for       2048 dirty pages
  get dirty log:    132 us for       4096 dirty pages
  get dirty log:    224 us for       8192 dirty pages
  get dirty log:    383 us for      16384 dirty pages
  get dirty log:    725 us for      32768 dirty pages
  get dirty log:   1412 us for      65536 dirty pages
  get dirty log:   2746 us for     131072 dirty pages
  get dirty log:   5455 us for     262144 dirty pages

Signed-off-by: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>
---
 api/dirty-log-perf.cc |  107 +++++++++++++++++++++++++++++++++++++++++++++++++
 config-x86-common.mak |    3 +
 2 files changed, 110 insertions(+), 0 deletions(-)
 create mode 100644 api/dirty-log-perf.cc

diff --git a/api/dirty-log-perf.cc b/api/dirty-log-perf.cc
new file mode 100644
index 0000000..83413ce
--- /dev/null
+++ b/api/dirty-log-perf.cc
@@ -0,0 +1,107 @@
+#include "kvmxx.hh"
+#include "memmap.hh"
+#include "identity.hh"
+#include <boost/thread/thread.hpp>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/time.h>
+
+namespace {
+
+const int page_size	= 4096;
+const int nr_pages	= 256 * 1024;
+
+void delay_loop(unsigned n)
+{
+    for (unsigned i = 0; i < n; ++i) {
+        asm volatile("pause");
+    }
+}
+
+void write_mem(volatile bool& running, volatile int& nr_dirty_pages,
+               void* logged_slot_virt)
+{
+    while (nr_dirty_pages >= 0) {
+        char* var = static_cast<char*>(logged_slot_virt);
+
+        while (!running) {
+            delay_loop(1000);
+        }
+        for (int i = 0; i < nr_dirty_pages; ++i) {
+            ++(*var);
+            var += page_size;
+        }
+        running = false;
+    }
+}
+
+void check_dirty_log(mem_slot& slot,
+                     volatile bool& running,
+                     volatile int& nr_dirty_pages)
+{
+    slot.set_dirty_logging(true);
+    slot.update_dirty_log();
+
+    for (int i = 1; i <= nr_pages; i *= 2) {
+        struct timeval start_time, end_time;
+        long time_usec;
+
+        nr_dirty_pages = i;
+        running = true;
+        // wait until the guest finishes writing
+        while (running) {
+            delay_loop(1000);
+        }
+
+        gettimeofday(&start_time, NULL);
+        slot.update_dirty_log();
+        gettimeofday(&end_time, NULL);
+
+        time_usec = 1000 * 1000 * (end_time.tv_sec - start_time.tv_sec);
+        time_usec += end_time.tv_usec - start_time.tv_usec;
+        printf("get dirty log: %6ld us for %10d dirty pages\n",
+               time_usec, nr_dirty_pages);
+    }
+
+    // stop the guest
+    nr_dirty_pages = -1;
+    running = true;
+    slot.set_dirty_logging(false);
+}
+
+}
+
+using boost::ref;
+using std::tr1::bind;
+
+int main(int ac, char **av)
+{
+    kvm::system sys;
+    kvm::vm vm(sys);
+    mem_map memmap(vm);
+
+    void* logged_slot_virt;
+    int memory_size = nr_pages * page_size;
+    if (posix_memalign(&logged_slot_virt, page_size, memory_size)) {
+        printf("dirty-log-perf: Could not allocate guest memory.\n");
+        exit(1);
+    }
+
+    identity::hole hole(logged_slot_virt, memory_size);
+    identity::vm ident_vm(vm, memmap, hole);
+    kvm::vcpu vcpu(vm, 0);
+    mem_slot logged_slot(memmap,
+                         reinterpret_cast<uint64_t>(logged_slot_virt),
+                         memory_size, logged_slot_virt);
+
+    bool running = false;
+    int nr_dirty_pages = 0;
+    boost::thread host_poll_thread(check_dirty_log, ref(logged_slot),
+                                   ref(running), ref(nr_dirty_pages));
+    identity::vcpu guest_write_thread(vcpu, bind(write_mem, ref(running),
+                                                 ref(nr_dirty_pages),
+                                                 logged_slot_virt));
+    vcpu.run();
+    host_poll_thread.join();
+    return 0;
+}
diff --git a/config-x86-common.mak b/config-x86-common.mak
index 1cbc7c6..a3e8ffa 100644
--- a/config-x86-common.mak
+++ b/config-x86-common.mak
@@ -39,6 +39,7 @@ tests-common = $(TEST_DIR)/vmexit.flat $(TEST_DIR)/tsc.flat \
 ifdef API
 tests-common += api/api-sample
 tests-common += api/dirty-log
+tests-common += api/dirty-log-perf
 endif
 
 tests_and_config = $(TEST_DIR)/*.flat $(TEST_DIR)/unittests.cfg
@@ -102,3 +103,5 @@ api/libapi.a: api/kvmxx.o api/identity.o api/exception.o api/memmap.o
 api/api-sample: api/api-sample.o api/libapi.a
 
 api/dirty-log: api/dirty-log.o api/libapi.a
+
+api/dirty-log-perf: api/dirty-log-perf.o api/libapi.a
-- 
1.7.5.4