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Re: [Qemu-devel] [PATCH v5 1/4] block: add the command line support
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v5 1/4] block: add the command line support |
Date: |
Wed, 10 Aug 2011 10:27:37 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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/
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.
> >> + /* 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:
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
[Qemu-devel] [PATCH v5 2/4] block: add the block queue support, Zhi Yong Wu, 2011/08/09