Re: [RFC PATCH 2/2] tests: Add dirty page rate limit test

[Hyman]

在 2022/3/10 16:29, Peter Xu 写道:
On Wed, Mar 09, 2022 at 11:58:01PM +0800, huang...@chinatelecom.cn wrote:
From: Hyman Huang(黄勇) <huang...@chinatelecom.cn>

Add dirty page rate limit test if kernel support dirty ring,
create a standalone file to implement the test case.

Thanks for writting this test case.


Signed-off-by: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
---
  tests/qtest/dirtylimit-test.c | 288 ++++++++++++++++++++++++++++++++++++++++++
  tests/qtest/meson.build       |   2 +
  2 files changed, 290 insertions(+)
  create mode 100644 tests/qtest/dirtylimit-test.c

diff --git a/tests/qtest/dirtylimit-test.c b/tests/qtest/dirtylimit-test.c
new file mode 100644
index 0000000..07eac2c
--- /dev/null
+++ b/tests/qtest/dirtylimit-test.c
@@ -0,0 +1,288 @@
+/*
+ * QTest testcase for Dirty Page Rate Limit
+ *
+ * Copyright (c) 2022 CHINA TELECOM CO.,LTD.
+ *
+ * Authors:
+ *  Hyman Huang(黄勇) <huang...@chinatelecom.cn>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "libqos/libqtest.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qlist.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi/qobject-output-visitor.h"
+
+#include "migration-helpers.h"
+#include "tests/migration/i386/a-b-bootblock.h"
+
+/*
+ * Dirtylimit stop working if dirty page rate error
+ * value less than DIRTYLIMIT_TOLERANCE_RANGE
+ */
+#define DIRTYLIMIT_TOLERANCE_RANGE  25  /* MB/s */
+
+static QDict *qmp_command(QTestState *who, const char *command, ...)
+{
+    va_list ap;
+    QDict *resp, *ret;
+
+    va_start(ap, command);
+    resp = qtest_vqmp(who, command, ap);
+    va_end(ap);
+
+    g_assert(!qdict_haskey(resp, "error"));
+    g_assert(qdict_haskey(resp, "return"));
+
+    ret = qdict_get_qdict(resp, "return");
+    qobject_ref(ret);
+    qobject_unref(resp);
+
+    return ret;
+}
+
+static void calc_dirty_rate(QTestState *who, uint64_t calc_time)
+{
+    qobject_unref(qmp_command(who,
+                    "{ 'execute': 'calc-dirty-rate',"
+                    "'arguments': { "
+                    "'calc-time': %ld,"
+                    "'mode': 'dirty-ring' }}",
+                    calc_time));
+}
+
+static QDict *query_dirty_rate(QTestState *who)
+{
+    return qmp_command(who, "{ 'execute': 'query-dirty-rate' }");
+}
+
+static void dirtylimit_set_all(QTestState *who, uint64_t dirtyrate)
+{
+    qobject_unref(qmp_command(who,
+                    "{ 'execute': 'set-vcpu-dirty-limit',"
+                    "'arguments': { "
+                    "'dirty-rate': %ld } }",
+                    dirtyrate));
+}
+
+static void cancel_vcpu_dirty_limit(QTestState *who)
+{
+    qobject_unref(qmp_command(who,
+                    "{ 'execute': 'cancel-vcpu-dirty-limit' }"));
+}
+
+static QDict *query_vcpu_dirty_limit(QTestState *who)
+{
+    QDict *rsp;
+
+    rsp = qtest_qmp(who, "{ 'execute': 'query-vcpu-dirty-limit' }");
+    g_assert(!qdict_haskey(rsp, "error"));
+    g_assert(qdict_haskey(rsp, "return"));
+
+    return rsp;
+}
+
+static int64_t get_dirty_rate(QTestState *who)
+{
+    QDict *rsp_return;
+    gchar *status;
+    QList *rates;
+    const QListEntry *entry;
+    QDict *rate;
+    int64_t dirtyrate;
+
+    rsp_return = query_dirty_rate(who);
+    g_assert(rsp_return);
+
+    status = g_strdup(qdict_get_str(rsp_return, "status"));
+    g_assert(status);
+    g_assert_cmpstr(status, ==, "measured");
+
+    rates = qdict_get_qlist(rsp_return, "vcpu-dirty-rate");
+    g_assert(rates && !qlist_empty(rates));
+
+    entry = qlist_first(rates);
+    g_assert(entry);
+
+    rate = qobject_to(QDict, qlist_entry_obj(entry));
+    g_assert(rate);
+
+    dirtyrate = qdict_get_try_int(rate, "dirty-rate", -1);
+
+    qobject_unref(rsp_return);
+    return dirtyrate;
+}
+
+static int64_t get_limit_rate(QTestState *who)
+{
+    QDict *rsp_return;
+    QList *rates;
+    const QListEntry *entry;
+    QDict *rate;
+    int64_t dirtyrate;
+
+    rsp_return = query_vcpu_dirty_limit(who);
+    g_assert(rsp_return);
+
+    rates = qdict_get_qlist(rsp_return, "return");
+    g_assert(rates && !qlist_empty(rates));
+
+    entry = qlist_first(rates);
+    g_assert(entry);
+
+    rate = qobject_to(QDict, qlist_entry_obj(entry));
+    g_assert(rate);
+
+    dirtyrate = qdict_get_try_int(rate, "limit-rate", -1);
+
+    qobject_unref(rsp_return);
+    return dirtyrate;
+}
+
+static QTestState *start_vm(void)
+{
+    QTestState *vm = NULL;
+    g_autofree gchar *cmd = NULL;
+    const char *arch = qtest_get_arch();
+    g_autofree char *bootpath = NULL;
+
+    if (strcmp(arch, "i386") != 0 && strcmp(arch, "x86_64") != 0) {
+        return NULL;
+    }

Perhaps assert() on x86_64?  Dirty ring support is checked earlier, so I
don't see how it'll fail... Very possible i386 will not ever support the
ring anyway.
Ok.That make code more clean.

+
+    bootpath = g_strdup_printf("%s/bootsect", tmpfs);
+    assert(sizeof(x86_bootsect) == 512);
+    init_bootfile(bootpath, x86_bootsect, sizeof(x86_bootsect));
+
+    cmd = g_strdup_printf("-accel kvm,dirty-ring-size=4096 -accel tcg "
+                          "-name dirtylimit-test,debug-threads=on "
+                          "-m 150M -smp 1 "
+                          "-serial file:%s/vm_serial "
+                          "-drive file=%s,format=raw ",
+                          tmpfs, bootpath);
+
+    vm = qtest_init(cmd);
+    return vm;
+}
+
+static void stop_vm(QTestState *vm)
+{
+    qtest_quit(vm);
+    cleanup("bootsect");
+    cleanup("vm_serial");
+}
+
+static void test_vcpu_dirty_limit(void)
+{
+    QTestState *vm;
+    int64_t origin_rate;
+    int64_t quota_rate;
+    int64_t rate ;
+    int max_try_count = 5;
+    int hit = 0;
+
+    if (!(vm = start_vm())) {
+        return;

If you could change above into assert, then no "if" here.

+    }
+
+    /* Wait for the first serial output from the vm*/
+    wait_for_serial("vm_serial");
+
+    /* Do dirtyrate measurement with calc time equals 1s */
+    calc_dirty_rate(vm, 1);
+
+    /* Sleep a little bit longer than calc time,
+     * and ensure dirtyrate measurement has been done
+     */
+    usleep(1200000);

Can we avoid using exact sleep numbers?  We need to guarantee the test
doesn't fail even if the scheduler decides to do weird things..

How about loop until fetching a result, but with a timeout?
Ok.

+
+    /* Query original dirty page rate */
+    origin_rate = get_dirty_rate(vm);
+
+    /* VM booted from bootsect should dirty memory */
+    assert(origin_rate != 0);
+
+    /* Setup quota dirty page rate at one-third of origin */
+    quota_rate = origin_rate / 3;
+
+    /* Set dirtylimit and wait a bit to check if it take effect */
+    dirtylimit_set_all(vm, quota_rate);
+    usleep(2000000);
+
+    /* Check if set-vcpu-dirty-limit and query-vcpu-dirty-limit
+     * works literally */
+    g_assert_cmpint(quota_rate, ==, get_limit_rate(vm));
+
+    /* Check if dirtylimit take effect realistically */
+    while (--max_try_count) {
+        calc_dirty_rate(vm, 1);
+        usleep(1200000);

Same here.

+        rate = get_dirty_rate(vm);
+
+        /* Assume hitting if current rate is less
+         * than quota rate (within accepting error)
+         */
+        if (rate < (quota_rate + DIRTYLIMIT_TOLERANCE_RANGE)) {
+            hit = 1;
+            break;
+        }
+    }
+
+    g_assert_cmpint(hit, ==, 1);
+
+    hit = 0;
+    max_try_count = 5;
+
+    /* Check if dirtylimit cancellation take effect */
+    cancel_vcpu_dirty_limit(vm);
+    while (--max_try_count) {
+        calc_dirty_rate(vm, 1);
+        usleep(1200000);

Same here.

+        rate = get_dirty_rate(vm);
+
+        /* Assume dirtylimit be canceled if current rate is
+         * greater than quota rate (within accepting error)
+         */
+        if (rate > (quota_rate + DIRTYLIMIT_TOLERANCE_RANGE)) {
+            hit = 1;
+            break;
+        }
+    }
+
+    g_assert_cmpint(hit, ==, 1);
+    stop_vm(vm);
+}

Thanks,

Ok, thanks Peter for commenting. I'll post the next version after 
patchset "support dirty restraint on vCPU" get merged, and hope more 
comments about the patch be given during the time.