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Re: [Qemu-devel] [RFC PATCH V5 1/4] colo-compare: introduce colo compare


From: Jason Wang
Subject: Re: [Qemu-devel] [RFC PATCH V5 1/4] colo-compare: introduce colo compare initialization
Date: Fri, 8 Jul 2016 17:12:26 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0



On 2016年07月08日 16:21, Zhang Chen wrote:


On 07/08/2016 11:40 AM, Jason Wang wrote:


On 2016年06月23日 19:34, Zhang Chen wrote:
Packets coming from the primary char indev will be sent to outdev
Packets coming from the secondary char dev will be dropped

usage:

primary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0

secondary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=red0,host=3.3.3.3,port=9003
-chardev socket,id=red1,host=3.3.3.3,port=9004
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1

Consider we finally want a non-rfc patch, it's better to have a some explanations on the above configurations since it was not easy to for starters at first glance.Maybe you can use either a ascii figure or a paragraph. Also need to explain the parameter of colo-compare in detail.

Make sense,I will add a ascii figure and some comments to explain it.



Signed-off-by: Zhang Chen <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
Signed-off-by: Wen Congyang <address@hidden>
---
  net/Makefile.objs  |   1 +
net/colo-compare.c | 231 +++++++++++++++++++++++++++++++++++++++++++++++++++++
  qemu-options.hx    |  34 ++++++++
  vl.c               |   3 +-
  4 files changed, 268 insertions(+), 1 deletion(-)
  create mode 100644 net/colo-compare.c

diff --git a/net/Makefile.objs b/net/Makefile.objs
index b7c22fd..ba92f73 100644
--- a/net/Makefile.objs
+++ b/net/Makefile.objs
@@ -16,3 +16,4 @@ common-obj-$(CONFIG_NETMAP) += netmap.o
  common-obj-y += filter.o
  common-obj-y += filter-buffer.o
  common-obj-y += filter-mirror.o
+common-obj-y += colo-compare.o
diff --git a/net/colo-compare.c b/net/colo-compare.c
new file mode 100644
index 0000000..a3e1456
--- /dev/null
+++ b/net/colo-compare.c
@@ -0,0 +1,231 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2016 FUJITSU LIMITED
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Author: Zhang Chen <address@hidden>
+ *
+ * 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 "qemu/error-report.h"
+#include "qemu-common.h"
+#include "qapi/qmp/qerror.h"
+#include "qapi/error.h"
+#include "net/net.h"
+#include "net/vhost_net.h"
+#include "qom/object_interfaces.h"
+#include "qemu/iov.h"
+#include "qom/object.h"
+#include "qemu/typedefs.h"
+#include "net/queue.h"
+#include "sysemu/char.h"
+#include "qemu/sockets.h"
+#include "qapi-visit.h"
+#include "trace.h"

Looks like trace were not really used in the patch, you can delay the inclusion until is was really used.

OK~~~


+
+#define TYPE_COLO_COMPARE "colo-compare"
+#define COLO_COMPARE(obj) \
+    OBJECT_CHECK(CompareState, (obj), TYPE_COLO_COMPARE)
+
+#define COMPARE_READ_LEN_MAX NET_BUFSIZE
+
+static QTAILQ_HEAD(, CompareState) net_compares =
+       QTAILQ_HEAD_INITIALIZER(net_compares);

What's the usage of this? A comment would be better.

If we need compare more than one netdev,we should use
more than one colo-compare. we do checkpoint should flush
all enqueued packet in colo-compare when work with colo-frame.
we use this queue to find all colo-compare.
So, look like no need here, I will move it to after patch.

Yes unless you want a single colo comparing threads to do comparing for all netdevs. (But I agree, looks not need).




+
+typedef struct CompareState {
+    Object parent;
+
+    char *pri_indev;
+    char *sec_indev;
+    char *outdev;
+    CharDriverState *chr_pri_in;
+    CharDriverState *chr_sec_in;
+    CharDriverState *chr_out;
+    QTAILQ_ENTRY(CompareState) next;
+    SocketReadState pri_rs;
+    SocketReadState sec_rs;
+} CompareState;
+
+typedef struct CompareClass {
+    ObjectClass parent_class;
+} CompareClass;
+
+static char *compare_get_pri_indev(Object *obj, Error **errp)
+{
+    CompareState *s = COLO_COMPARE(obj);
+
+    return g_strdup(s->pri_indev);
+}
+
+static void compare_set_pri_indev(Object *obj, const char *value, Error **errp)
+{
+    CompareState *s = COLO_COMPARE(obj);
+
+    g_free(s->pri_indev);
+    s->pri_indev = g_strdup(value);

I think we need do something more than this, e.g release the orig dev and get the new one? Or just forbid setting this property.


Do you means that:
qemu_chr_fe_release(s->chr_pri_in);

If yes,in here we just get/set char* pri_indev(chardev's name).
We don't get or set CharDriverState, so I think we needn't do more.

Maybe I miss something, but is there any usage for just changing chardev's name here?



And looks like we have similar issues for sec_indev and outdev.

+}
+


[...]

+
+static void colo_compare_finalize(Object *obj)
+{
+    CompareState *s = COLO_COMPARE(obj);
+
+    if (s->chr_pri_in) {
+        qemu_chr_add_handlers(s->chr_pri_in, NULL, NULL, NULL, NULL);

Why need do this?

more safty before do qemu_chr_fe_release() for chardev
like backends/rng-egd.c

Ok, but looks like we don't set any handlers in the patch, so I don't get why need to clear it.

For the things of eng-egd, I think we need fail if it was not a socket chardev. Vhost-use did similar check in net_vhost_chardev_opts() which maybe useful for here (we probably need this for mirror/redirector too).

[...]



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