Re: [Qemu-devel] [PATCH v5 1/4] block: add the command line support

[Zhi Yong Wu]

On Wed, Aug 10, 2011 at 5:27 PM, Stefan Hajnoczi
<address@hidden> wrote:
> On Wed, Aug 10, 2011 at 01:20:22PM +0800, Zhi Yong Wu wrote:
>> On Tue, Aug 9, 2011 at 8:25 PM, Stefan Hajnoczi <address@hidden> wrote:
>> > On Tue, Aug 9, 2011 at 5:17 AM, Zhi Yong Wu <address@hidden> wrote:
>> >> Signed-off-by: Zhi Yong Wu <address@hidden>
>> >> ---
>> >>  Makefile.objs   |    2 +-
>> >>  blockdev.c      |   39 +++++++++++++++++++++++++++++++++++++++
>> >>  qemu-config.c   |   24 ++++++++++++++++++++++++
>> >>  qemu-option.c   |   17 +++++++++++++++++
>> >>  qemu-option.h   |    1 +
>> >>  qemu-options.hx |    1 +
>> >>  6 files changed, 83 insertions(+), 1 deletions(-)
>> >>
>> >> diff --git a/Makefile.objs b/Makefile.objs
>> >> index 9f99ed4..06f2033 100644
>> >> --- a/Makefile.objs
>> >> +++ b/Makefile.objs
>> >> @@ -23,7 +23,7 @@ block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o 
>> >> cloop.o dmg.o bochs.o vpc.o vv
>> >>  block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o 
>> >> qcow2-snapshot.o qcow2-cache.o
>> >>  block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o 
>> >> qed-cluster.o
>> >>  block-nested-y += qed-check.o
>> >> -block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
>> >> +block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o 
>> >> blk-queue.o
>> >
>> > This does not build:
>> >  LINK  qemu-ga
>> > gcc: error: block/blk-queue.o: No such file or directory
>> >
>> > This Makefile.objs change should be in the commit that adds blk-queue.c.
>> >
>> > Each patch in a series should compile cleanly and can only depend on
>> > previous patches.  This is important so that git-bisect(1) can be
>> > used, it only works if every commit builds a working program.  It also
>> > makes patch review easier when the patch series builds up logically.
>> It seems that it will take a bit much time if we strictly stage the
>> hunks into each corresponding patch.:)
>> OK, i will.
>
> Some people like using Stacked Git to manage patch series:
> http://www.procode.org/stgit/
Let me try.
>
> I typically just use git rebase -i and git add -i manually to clean up
> patch series.
>
> It also becomes easier once you plan to write patches that follow these
> guidelines.
OK
>
>> >> +    /* disk io throttling */
>> >> +    iol_flag = qemu_opt_io_limits_enable_flag(opts, iol_opts);
>> >> +    if (iol_flag) {
>> >> +        memset(&io_limits, 0, sizeof(BlockIOLimit));
>> >> +
>> >> +        io_limits.bps[BLOCK_IO_LIMIT_TOTAL]  =
>> >> +                           qemu_opt_get_number(opts, "bps", 0);
>> >> +        io_limits.bps[BLOCK_IO_LIMIT_READ]   =
>> >> +                           qemu_opt_get_number(opts, "bps_rd", 0);
>> >> +        io_limits.bps[BLOCK_IO_LIMIT_WRITE]  =
>> >> +                           qemu_opt_get_number(opts, "bps_wr", 0);
>> >> +        io_limits.iops[BLOCK_IO_LIMIT_TOTAL] =
>> >> +                           qemu_opt_get_number(opts, "iops", 0);
>> >> +        io_limits.iops[BLOCK_IO_LIMIT_READ]  =
>> >> +                           qemu_opt_get_number(opts, "iops_rd", 0);
>> >> +        io_limits.iops[BLOCK_IO_LIMIT_WRITE] =
>> >> +                           qemu_opt_get_number(opts, "iops_wr", 0);
>> >> +
>> >> +        if (((io_limits.bps[BLOCK_IO_LIMIT_TOTAL] != 0)
>> >> +            && ((io_limits.bps[BLOCK_IO_LIMIT_READ] != 0)
>> >> +            || (io_limits.bps[BLOCK_IO_LIMIT_WRITE] != 0)))
>> >> +            || ((io_limits.iops[BLOCK_IO_LIMIT_TOTAL] != 0)
>> >> +            && ((io_limits.iops[BLOCK_IO_LIMIT_READ] != 0)
>> >> +            || (io_limits.iops[BLOCK_IO_LIMIT_WRITE] != 0)))) {
>> >> +            error_report("bps(iops) and bps_rd/bps_wr(iops_rd/iops_wr) \
>> >> +                                        cannot be used at the same 
>> >> time");
>> >> +            return NULL;
>> >> +        }
>> >> +    }
>> >> +
>> >>     on_write_error = BLOCK_ERR_STOP_ENOSPC;
>> >>     if ((buf = qemu_opt_get(opts, "werror")) != NULL) {
>> >>         if (type != IF_IDE && type != IF_SCSI && type != IF_VIRTIO && 
>> >> type != IF_NONE) {
>> >> @@ -483,6 +517,11 @@ DriveInfo *drive_init(QemuOpts *opts, int 
>> >> default_to_scsi)
>> >>
>> >>     bdrv_set_on_error(dinfo->bdrv, on_read_error, on_write_error);
>> >>
>> >> +    /* disk I/O throttling */
>> >> +    if (iol_flag) {
>> >> +        bdrv_set_io_limits(dinfo->bdrv, &io_limits);
>> >> +    }
>> >
>> > iol_flag and qemu_opt_io_limits_enable_flag() are not necessary.  If
>> > no limits were set then all fields will be 0 (unlimited).
>> Are they not necessary here? why? qemu_opt_io_limits_enable_flag is
>> used to determine if io_limits is enabled.
>> If yes, iol_flag will be set to ONE. So i think that they are necessay here.
>
> There are two possible cases: the user does not set any options or the
> user sets at least one option.  In both cases io_limits will be
> initialized correctly, here is why:
>
> When an option is not specified by the user the value will be 0, which
> means "unlimited".  bdrv_set_io_limits() calls
> bdrv_io_limits_enabled(bs) to check whether any I/O limit is non-zero.
> This means the iol_flag check is already being done by
> bdrv_set_io_limits() and there is no need to duplicate it.  The iol_flag
> code can be eliminated and the program will behave the same.
>
> The code would look something like this:
If the user doesn't set any io_limits options, this chunk of codes are
also executed. anyway, that's OK. thanks.
>
> io_limits.bps[BLOCK_IO_LIMIT_TOTAL]  =
>                    qemu_opt_get_number(opts, "bps", 0);
> io_limits.bps[BLOCK_IO_LIMIT_READ]   =
>                    qemu_opt_get_number(opts, "bps_rd", 0);
> io_limits.bps[BLOCK_IO_LIMIT_WRITE]  =
>                    qemu_opt_get_number(opts, "bps_wr", 0);
> io_limits.iops[BLOCK_IO_LIMIT_TOTAL] =
>                    qemu_opt_get_number(opts, "iops", 0);
> io_limits.iops[BLOCK_IO_LIMIT_READ]  =
>                    qemu_opt_get_number(opts, "iops_rd", 0);
> io_limits.iops[BLOCK_IO_LIMIT_WRITE] =
>                   qemu_opt_get_number(opts, "iops_wr", 0);
>
> if (((io_limits.bps[BLOCK_IO_LIMIT_TOTAL] != 0)
>     && ((io_limits.bps[BLOCK_IO_LIMIT_READ] != 0)
>     || (io_limits.bps[BLOCK_IO_LIMIT_WRITE] != 0)))
>     || ((io_limits.iops[BLOCK_IO_LIMIT_TOTAL] != 0)
>     && ((io_limits.iops[BLOCK_IO_LIMIT_READ] != 0)
>     || (io_limits.iops[BLOCK_IO_LIMIT_WRITE] != 0)))) {
>     error_report("bps(iops) and bps_rd/bps_wr(iops_rd/iops_wr) "
>                 "cannot be used at the same time");
>    return NULL;
> }
>
> bdrv_set_io_limits(dinfo->bdrv, &io_limits);
>
> Stefan
>



-- 
Regards,

Zhi Yong Wu