Skip to content

Q
qemu

openeuler / qemu

通知 10
Star 0
Fork 0
Q
qemu

体验新版 GitCode，发现更多精彩内容 >>

切换分支/标签
  1. 08 6月, 2016 2 次提交
  3. 12 5月, 2016 3 次提交
    • E
      block: Honor BDRV_REQ_FUA during write_zeroes · 465fe887
      由 Eric Blake 提交于 
      The block layer has a couple of cases where it can lose
Force Unit Access semantics when writing a large block of
zeroes, such that the request returns before the zeroes
have been guaranteed to land on underlying media.

SCSI does not support FUA during WRITESAME(10/16); FUA is only
supported if it falls back to WRITE(10/16).  But where the
underlying device is new enough to not need a fallback, it
means that any upper layer request with FUA semantics was
silently ignoring BDRV_REQ_FUA.

Conversely, NBD has situations where it can support FUA but not
ZERO_WRITE; when that happens, the generic block layer fallback
to bdrv_driver_pwritev() (or the older bdrv_co_writev() in qemu
2.6) was losing the FUA flag.

The problem of losing flags unrelated to ZERO_WRITE has been
latent in bdrv_co_do_write_zeroes() since commit aa7bfbff, but
back then, it did not matter because there was no FUA flag.  It
became observable when commit 93f5e6d8 paved the way for flags
that can impact correctness, when we should have been using
bdrv_co_writev_flags() with modified flags.  Compare to commit
9eeb6dd1, which got flag manipulation right in
bdrv_co_do_zero_pwritev().

Symptoms: I tested with qemu-io with default writethrough cache
(which is supposed to use FUA semantics on every write), and
targetted an NBD client connected to a server that intentionally
did not advertise NBD_FLAG_SEND_FUA.  When doing 'write 0 512',
the NBD client sent two operations (NBD_CMD_WRITE then
NBD_CMD_FLUSH) to get the fallback FUA semantics; but when doing
'write -z 0 512', the NBD client sent only NBD_CMD_WRITE.

The fix is do to a cleanup bdrv_co_flush() at the end of the
operation if any step in the middle relied on a BDS that does
not natively support FUA for that step (note that we don't
need to flush after every operation, if the operation is broken
into chunks based on bounce-buffer sizing).  Each BDS gains a
new flag .supported_zero_flags, which parallels the use of
.supported_write_flags but only when accessing a zero write
operation (the flags MUST be different, because of SCSI having
different semantics based on WRITE vs. WRITESAME; and also
because BDRV_REQ_MAY_UNMAP only makes sense on zero writes).

Also fix some documentation to describe -ENOTSUP semantics,
particularly since iscsi depends on those semantics.

Down the road, we may want to add a driver where its
.bdrv_co_pwritev() honors all three of BDRV_REQ_FUA,
BDRV_REQ_ZERO_WRITE, and BDRV_REQ_MAY_UNMAP, and advertise
this via bs->supported_write_flags for blocks opened by that
driver; such a driver should NOT supply .bdrv_co_write_zeroes
nor .supported_zero_flags.  But none of the drivers touched
in this patch want to do that (the act of writing zeroes is
different enough from normal writes to deserve a second
callback).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      465fe887
    • P
      linux-aio: make it more type safe · dd7f7ed1
      由 Paolo Bonzini 提交于 
      Replace void* with an opaque LinuxAioState type.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      dd7f7ed1
    • P
      block: plug whole tree at once, introduce bdrv_io_unplugged_begin/end · 6b98bd64
      由 Paolo Bonzini 提交于 
      Extract the handling of io_plug "depth" from linux-aio.c and let the
main bdrv_drain loop do nothing but wait on I/O.

Like the two newly introduced functions, bdrv_io_plug and bdrv_io_unplug
now operate on all children.  The visit order is now symmetrical between
plug and unplug, making it possible for formats to implement plug/unplug.
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      6b98bd64
  5. 30 3月, 2016 1 次提交
  7. 23 3月, 2016 2 次提交
    • V
      util: move declarations out of qemu-common.h · f348b6d1
      由 Veronia Bahaa 提交于 
      Move declarations out of qemu-common.h for functions declared in
utils/ files: e.g. include/qemu/path.h for utils/path.c.
Move inline functions out of qemu-common.h and into new files (e.g.
include/qemu/bcd.h)
Signed-off-by: NVeronia Bahaa <veroniabahaa@gmail.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      f348b6d1
    • M
      include/qemu/osdep.h: Don't include qapi/error.h · da34e65c
      由 Markus Armbruster 提交于 
      Commit 57cb38b3 included qapi/error.h into qemu/osdep.h to get the
Error typedef.  Since then, we've moved to include qemu/osdep.h
everywhere.  Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h.  That's in excess of
100KiB of crap most .c files don't actually need.

Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h.  Include qapi/error.h in .c files that need it and don't
get it now.  Include qapi-types.h in qom/object.h for uint16List.

Update scripts/clean-includes accordingly.  Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h.  Update the list of includes in the qemu/osdep.h
comment quoted above similarly.

This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third.  Unfortunately, the number depending on
qapi-types.h shrinks only a little.  More work is needed for that one.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
[Fix compilation without the spice devel packages. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      da34e65c
  9. 03 2月, 2016 2 次提交
  11. 20 1月, 2016 2 次提交
  13. 18 12月, 2015 1 次提交
  15. 17 12月, 2015 1 次提交
    • E
      qapi: Don't let implicit enum MAX member collide · 7fb1cf16
      由 Eric Blake 提交于 
      Now that we guarantee the user doesn't have any enum values
beginning with a single underscore, we can use that for our
own purposes.  Renaming ENUM_MAX to ENUM__MAX makes it obvious
that the sentinel is generated.

This patch was mostly generated by applying a temporary patch:

|diff --git a/scripts/qapi.py b/scripts/qapi.py
|index e6d014b..b862ec9 100644
|--- a/scripts/qapi.py
|+++ b/scripts/qapi.py
|@@ -1570,6 +1570,7 @@ const char *const %(c_name)s_lookup[] = {
|     max_index = c_enum_const(name, 'MAX', prefix)
|     ret += mcgen('''
|     [%(max_index)s] = NULL,
|+// %(max_index)s
| };
| ''',
|                max_index=max_index)

then running:

$ cat qapi-{types,event}.c tests/test-qapi-types.c |
    sed -n 's,^// \(.*\)MAX,s|\1MAX|\1_MAX|g,p' > list
$ git grep -l _MAX | xargs sed -i -f list

The only things not generated are the changes in scripts/qapi.py.

Rejecting enum members named 'MAX' is now useless, and will be dropped
in the next patch.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-23-git-send-email-eblake@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
[Rebased to current master, commit message tweaked]
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
      7fb1cf16
  17. 25 11月, 2015 1 次提交
  19. 12 11月, 2015 1 次提交
  21. 24 10月, 2015 2 次提交
  23. 16 10月, 2015 1 次提交
  25. 12 10月, 2015 1 次提交
  27. 02 10月, 2015 1 次提交
  29. 05 9月, 2015 1 次提交
    • M
      block/raw-posix: Use raw_normalize_devicepath() · bdd03cdf
      由 Max Reitz 提交于 
      The filename given to qemu_open() in block/raw-posix.c should generally
have been processed by raw_normalize_devicepath(); unless we are only
probing (in which case the caller often checks whether the file is a
block device or not, and this property will be changed by
raw_normalize_devicepath() on NetBSD) or it is about a deprecated device
(i.e. floppy).
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      bdd03cdf
  31. 07 7月, 2015 1 次提交
    • R
      block/raw-posix: Don't think /dev/fd/<NN> is a floppy drive. · 25d9747b
      由 Richard W.M. Jones 提交于 
      In libguestfs we use /dev/fd/<NN> to pass pre-opened file descriptors
to qemu-img.  Lately I've discovered that although this works, qemu
believes that these are floppy disk images.  That in itself isn't much
of a problem, but now qemu prints a warning about host floppy
pass-thru being deprecated.

Extend the existing test so that it ignores /dev/fd/ as well as
/dev/fdset/

A simple test of this, if you are using the bash shell, is:

  qemu-img info <( cat /dev/null )

without this patch:

  $ qemu-img info <( cat /dev/null )
  qemu-img: Host floppy pass-through is deprecated
  Support for it will be removed in a future release.
  qemu-img: Could not open '/dev/fd/63': Could not refresh total sector count: Illegal seek

with this patch:

  $ qemu-img info <( cat /dev/null )
  qemu-img: Could not open '/dev/fd/63': Could not refresh total sector count: Illegal seek
Signed-off-by: NRichard W.M. Jones <rjones@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Message-id: 1435761614-31358-1-git-send-email-rjones@redhat.com
Fixes: https://bugs.launchpad.net/qemu/+bug/1470536Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      25d9747b
  33. 23 6月, 2015 5 次提交
  35. 12 6月, 2015 2 次提交
  37. 22 5月, 2015 2 次提交
    • D
      block: align bounce buffers to page · 459b4e66
      由 Denis V. Lunev 提交于 
      The following sequence
    int fd = open(argv[1], O_RDWR | O_CREAT | O_DIRECT, 0644);
    for (i = 0; i < 100000; i++)
            write(fd, buf, 4096);
performs 5% better if buf is aligned to 4096 bytes.

The difference is quite reliable.

On the other hand we do not want at the moment to enforce bounce
buffering if guest request is aligned to 512 bytes.

The patch changes default bounce buffer optimal alignment to
MAX(page size, 4k). 4k is chosen as maximal known sector size on real
HDD.

The justification of the performance improve is quite interesting.
From the kernel point of view each request to the disk was split
by two. This could be seen by blktrace like this:
  9,0   11  1     0.000000000 11151  Q  WS 312737792 + 1023 [qemu-img]
  9,0   11  2     0.000007938 11151  Q  WS 312738815 + 8 [qemu-img]
  9,0   11  3     0.000030735 11151  Q  WS 312738823 + 1016 [qemu-img]
  9,0   11  4     0.000032482 11151  Q  WS 312739839 + 8 [qemu-img]
  9,0   11  5     0.000041379 11151  Q  WS 312739847 + 1016 [qemu-img]
  9,0   11  6     0.000042818 11151  Q  WS 312740863 + 8 [qemu-img]
  9,0   11  7     0.000051236 11151  Q  WS 312740871 + 1017 [qemu-img]
  9,0    5  1     0.169071519 11151  Q  WS 312741888 + 1023 [qemu-img]
After the patch the pattern becomes normal:
  9,0    6  1     0.000000000 12422  Q  WS 314834944 + 1024 [qemu-img]
  9,0    6  2     0.000038527 12422  Q  WS 314835968 + 1024 [qemu-img]
  9,0    6  3     0.000072849 12422  Q  WS 314836992 + 1024 [qemu-img]
  9,0    6  4     0.000106276 12422  Q  WS 314838016 + 1024 [qemu-img]
and the amount of requests sent to disk (could be calculated counting
number of lines in the output of blktrace) is reduced about 2 times.

Both qemu-img and qemu-io are affected while qemu-kvm is not. The guest
does his job well and real requests comes properly aligned (to page).
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1431441056-26198-3-git-send-email-den@openvz.org
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      459b4e66
    • D
      block: minimal bounce buffer alignment · 4196d2f0
      由 Denis V. Lunev 提交于 
      The patch introduces new concept: minimal memory alignment for bounce
buffers. Original so called "optimal" value is actually minimal required
value for aligment. It should be used for validation that the IOVec
is properly aligned and bounce buffer is not required.

Though, from the performance point of view, it would be better if
bounce buffer or IOVec allocated by QEMU will be aligned stricter.

The patch does not change any alignment value yet.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1431441056-26198-2-git-send-email-den@openvz.org
CC: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
      4196d2f0
  39. 19 3月, 2015 2 次提交
  41. 10 3月, 2015 3 次提交
  43. 09 3月, 2015 1 次提交
    • D
      block/raw-posix: fix compilation warning on OSX · a6dcf097
      由 Denis V. Lunev 提交于 
      block/raw-posix.c:947:19: warning: unused variable 's' [-Wunused-variable]
    BDRVRawState *s = aiocb->bs->opaque;

This variable is used only when on of the following macros are defined
CONFIG_XFS, CONFIG_FALLOCATE, CONFIG_FALLOCATE_PUNCH_HOLE or
CONFIG_FALLOCATE_ZERO_RANGE. Fortunately, CONFIG_FALLOCATE_PUNCH_HOLE
and CONFIG_FALLOCATE_ZERO_RANGE could be defined only along with
CONFIG_FALLOCATE. Therefore checking for CONFIG_XFS or CONFIG_FALLOCATE
would be enough.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
CC: Peter Maydell <peter.maydell@linaro.org>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
      a6dcf097
  45. 16 2月, 2015 1 次提交
  47. 07 2月, 2015 1 次提交