Re: [Qemu-devel] [PATCH V2] qemu-img: make convert async

[Kevin Wolf <kwolf@redhat.com>]

Am 28.02.2017 um 10:59 hat Peter Lieven geschrieben:
> Am 27.02.2017 um 22:09 schrieb Eric Blake:
> >On 02/27/2017 05:03 AM, Peter Lieven wrote:
> >>the convert process is currently completely implemented with sync operations.
> >>That means it reads one buffer and then writes it. No parallelism and each sync
> >>request takes as long as it takes until it is completed.
> >>
> >>This patches introduces 2 new cmdline parameters. The -m parameter to specify
> >>the number of coroutines running in parallel (defaults to 8). And the -W paremeter to
> >s/paremeter/parameter/
> >
> >>allow qemu-img to write to the target out of order rather than sequential. This improves
> >>performance as the writes do not have to wait for each other to complete.
> >>
> >>Signed-off-by: Peter Lieven <pl@kamp.de>
> >>---
> >>@@ -1798,7 +1908,7 @@ static int img_convert(int argc, char **argv)
> >>              {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
> >>              {0, 0, 0, 0}
> >>          };
> >>-        c = getopt_long(argc, argv, "hf:O:B:ce6o:s:l:S:pt:T:qn",
> >>+        c = getopt_long(argc, argv, "hf:O:B:ce6o:s:l:S:pt:T:qnm:W",
> >>                          long_options, NULL);
> >>          if (c == -1) {
> >>              break;
> >>@@ -1890,6 +2000,18 @@ static int img_convert(int argc, char **argv)
> >>          case 'n':
> >>              skip_create = 1;
> >>              break;
> >>+        case 'm':
> >>+            num_coroutines = atoi(optarg);
> >atoi() should be avoided. It has no error checking, so it treats '-m 1'
> >and '-m 1k' identically.  You are a bit justified in that '-m junk' gets
> >treated like '-m 0' and rejected, but it's still a poor error message in
> >that case.
> 
> would you use qemu_strtoul or parse_uint instead?
> 
> Kevin, shall I send a V3?

If you can send a v3 today, I'll replace the patch in my queue with it.
Otherwise we'll fix it on top during the freeze.

Kevin