[v2,1/2] qemu-img: add support for offline rate limit in qemu-img commit

Commit Message

Zhengui li Oct. 20, 2020, 11:39 a.m. UTC

From: Zhengui <[e-mail]>

Currently, there is no rate limit for qemu-img commit. This may
cause the task of qemu-img commit to consume all the bandwidth
of the storage. This will affect the IO performance of other processes
and virtual machines under shared storage. So we add support for
offline rate limit in qemu-img commit to get better quality of sevice.

Signed-off-by: Zhengui <[e-mail]>
---
 docs/tools/qemu-img.rst |  4 +++-
 qemu-img-cmds.hx        |  4 ++--
 qemu-img.c              | 14 ++++++++++++--
 3 files changed, 17 insertions(+), 5 deletions(-)

Comments

Alberto Garcia Oct. 20, 2020, 12:10 p.m. UTC | #1

On Tue 20 Oct 2020 01:39:05 PM CEST, Zhengui li wrote:
> From: Zhengui <[e-mail]>
>
> Currently, there is no rate limit for qemu-img commit. This may
> cause the task of qemu-img commit to consume all the bandwidth
> of the storage. This will affect the IO performance of other processes
> and virtual machines under shared storage. So we add support for
> offline rate limit in qemu-img commit to get better quality of sevice.
>
> Signed-off-by: Zhengui <[e-mail]>

Thanks for the patch!

When you send more than one patch you should add a cover letter (you can
use git format-patch --cover-letter).

See https://wiki.qemu.org/Contribute/SubmitAPatch#Include_a_meaningful_cover_letter

> +        case 'r': {
> +            int64_t sval;
> +
> +            sval = cvtnum("rate limit", optarg);
> +            if (sval < 0) {
> +                return 1;
> +            }
> +            rate_limit = sval;
> +        }   break;

I don't think you need sval here, do you?

rate_limit = cvtnum(...);
if (rate_limit < 0) {
    return 1;
}

Like that you can also get rid of the extra braces { }

Other than that the patch looks correct.

With that changed,

Reviewed-by: Alberto Garcia <[e-mail]>

Berto

Patch

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index c35bd64..bcb11b0 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -349,7 +349,7 @@  Command description:
   state after (the attempt at) repairing it. That is, a successful ``-r all``
   will yield the exit code 0, independently of the image state before.
 
-.. option:: commit [--object OBJECTDEF] [--image-opts] [-q] [-f FMT] [-t CACHE] [-b BASE] [-d] [-p] FILENAME
+.. option:: commit [--object OBJECTDEF] [--image-opts] [-q] [-f FMT] [-t CACHE] [-b BASE] [-r RATE_LIMIT] [-d] [-p] FILENAME
 
   Commit the changes recorded in *FILENAME* in its base image or backing file.
   If the backing file is smaller than the snapshot, then the backing file will be
@@ -371,6 +371,8 @@  Command description:
   garbage data when read. For this reason, ``-b`` implies ``-d`` (so that
   the top image stays valid).
 
+  The rate limit for the commit process is specified by ``-r``.
+
 .. option:: compare [--object OBJECTDEF] [--image-opts] [-f FMT] [-F FMT] [-T SRC_CACHE] [-p] [-q] [-s] [-U] FILENAME1 FILENAME2
 
   Check if two images have the same content. You can compare images with
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index b89c019..2a31806 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -34,9 +34,9 @@  SRST
 ERST
 
 DEF("commit", img_commit,
-    "commit [--object objectdef] [--image-opts] [-q] [-f fmt] [-t cache] [-b base] [-d] [-p] filename")
+    "commit [--object objectdef] [--image-opts] [-q] [-f fmt] [-t cache] [-b base] [-r rate_limit] [-d] [-p] filename")
 SRST
-.. option:: commit [--object OBJECTDEF] [--image-opts] [-q] [-f FMT] [-t CACHE] [-b BASE] [-d] [-p] FILENAME
+.. option:: commit [--object OBJECTDEF] [--image-opts] [-q] [-f FMT] [-t CACHE] [-b BASE] [-r RATE_LIMIT] [-d] [-p] FILENAME
 ERST
 
 DEF("compare", img_compare,
diff --git a/qemu-img.c b/qemu-img.c
index 2103507..ea66139 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -980,6 +980,7 @@  static int img_commit(int argc, char **argv)
     CommonBlockJobCBInfo cbi;
     bool image_opts = false;
     AioContext *aio_context;
+    int64_t rate_limit = 0;
 
     fmt = NULL;
     cache = BDRV_DEFAULT_CACHE;
@@ -991,7 +992,7 @@  static int img_commit(int argc, char **argv)
             {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
             {0, 0, 0, 0}
         };
-        c = getopt_long(argc, argv, ":f:ht:b:dpq",
+        c = getopt_long(argc, argv, ":f:ht:b:dpqr:",
                         long_options, NULL);
         if (c == -1) {
             break;
@@ -1026,6 +1027,15 @@  static int img_commit(int argc, char **argv)
         case 'q':
             quiet = true;
             break;
+        case 'r': {
+            int64_t sval;
+
+            sval = cvtnum("rate limit", optarg);
+            if (sval < 0) {
+                return 1;
+            }
+            rate_limit = sval;
+        }   break;
         case OPTION_OBJECT: {
             QemuOpts *opts;
             opts = qemu_opts_parse_noisily(&qemu_object_opts,
@@ -1099,7 +1109,7 @@  static int img_commit(int argc, char **argv)
 
     aio_context = bdrv_get_aio_context(bs);
     aio_context_acquire(aio_context);
-    commit_active_start("commit", bs, base_bs, JOB_DEFAULT, 0,
+    commit_active_start("commit", bs, base_bs, JOB_DEFAULT, rate_limit,
                         BLOCKDEV_ON_ERROR_REPORT, NULL, common_block_job_cb,
                         &cbi, false, &local_err);
     aio_context_release(aio_context);