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* [Qemu-devel] [PATCH 0/3] Remove ->bdrv_pread() internal block layer API (v2)
@ 2009-03-12 12:57 Avi Kivity
  2009-03-12 12:57 ` [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API Avi Kivity
                   ` (3 more replies)
  0 siblings, 4 replies; 12+ messages in thread
From: Avi Kivity @ 2009-03-12 12:57 UTC (permalink / raw)
  To: Anthony Liguori; +Cc: qemu-devel

The internal block layer API has a wart in the form of the
->bdrv_pread() and ->bdrv_pwrite() methods.  These duplicate
bdrv_read() and bdrv_write(), and are unnatural for a block
device in that they are not sector oriented.

One of the reasons for their existence is the scsi-generic host support.
That is also a wart, as scsi-generic is really a packet (command/response)
rather than a block (random access to sectors) API.  There is also the
wierd negative sector count == byte count thing.

This patchset addresses these warts by adding a new API for scsi-generic
and dropping ->bdrv_pread() and bdrv_pwrite().  While the improvement
falls short of spectacular, it does make further hacking on the block
layer easier as there are fewer callbacks to worry about.

---

Changes since v1:
- rebased against trunk
- performance testing: tested 'rm -rf *; tar xjf ../linux-2.6.22.tar.bz2'
  with a vm snapshot.  While there are significant variances among runs
  (15-25sec), likely due to different ext3 allocation decisions and different
  host caching decisions, there seems to be no regression due to this patchset.

Avi Kivity (3):
  Add specialized block driver scsi generic API
  Add internal scsi generic block API
  Drop internal bdrv_pread()/bdrv_pwrite() APIs

 block-raw-posix.c |   50 ++++++++++++++++++++++++--
 block-raw-win32.c |   20 ++++++----
 block.c           |  101 +++++++++++++++--------------------------------------
 block.h           |    8 ++++
 block_int.h       |   14 +++++--
 hw/scsi-generic.c |   39 +++++++++++---------
 6 files changed, 126 insertions(+), 106 deletions(-)

^ permalink raw reply	[flat|nested] 12+ messages in thread
* [Qemu-devel] [PATCH 0/3] Remove ->bdrv_pread() internal block layer API
@ 2009-02-08 17:59 Avi Kivity
  2009-02-08 17:59 ` [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API Avi Kivity
  0 siblings, 1 reply; 12+ messages in thread
From: Avi Kivity @ 2009-02-08 17:59 UTC (permalink / raw)
  To: Anthony Liguori, qemu-devel

The internal block layer API has a wart in the form of the
->bdrv_pread() and ->bdrv_pwrite() methods.  These duplicate
bdrv_read() and bdrv_write(), and are unnatural for a block
device in that they are not sector oriented.

One of the reasons for their existence is the scsi-generic host support.
That is also a wart, as scsi-generic is really a packet (command/response)
rather than a block (random access to sectors) API.  There is also the
wierd negative sector count == byte count thing.

This patchset addresses these warts by adding a new API for scsi-generic
and dropping ->bdrv_pread() and bdrv_pwrite().  While the improvement
falls short of spectacular, it does make further hacking on the block
layer easier as there are fewer callbacks to worry about.

Avi Kivity (3):
  Add specialized block driver scsi generic API
  Add internal scsi generic block API
  Drop internal bdrv_pread()/bdrv_pwrite() APIs

 block-raw-posix.c |   50 +++++++++++++++++++++++++--
 block-raw-win32.c |   20 +++++++----
 block.c           |   95 +++++++++++++++-------------------------------------
 block.h           |    8 ++++
 block_int.h       |   14 +++++--
 hw/scsi-generic.c |   39 ++++++++++++---------
 6 files changed, 126 insertions(+), 100 deletions(-)

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2009-03-16 17:29 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-03-12 12:57 [Qemu-devel] [PATCH 0/3] Remove ->bdrv_pread() internal block layer API (v2) Avi Kivity
2009-03-12 12:57 ` [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API Avi Kivity
2009-03-14 14:33   ` Christoph Hellwig
2009-03-15 13:54     ` Avi Kivity
2009-03-15 14:43       ` Christoph Hellwig
2009-03-15 14:57         ` Avi Kivity
2009-03-15 15:06           ` Christoph Hellwig
2009-03-16 17:29           ` Jamie Lokier
2009-03-12 12:57 ` [Qemu-devel] [PATCH 2/3] Add internal scsi generic block API Avi Kivity
2009-03-12 12:57 ` [Qemu-devel] [PATCH 3/3] Drop internal bdrv_pread()/bdrv_pwrite() APIs Avi Kivity
2009-03-12 19:57 ` [Qemu-devel] Re: [PATCH 0/3] Remove ->bdrv_pread() internal block layer API (v2) Anthony Liguori
  -- strict thread matches above, loose matches on Subject: below --
2009-02-08 17:59 [Qemu-devel] [PATCH 0/3] Remove ->bdrv_pread() internal block layer API Avi Kivity
2009-02-08 17:59 ` [Qemu-devel] [PATCH 1/3] Add specialized block driver scsi generic API Avi Kivity

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