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2008-10-14Expand cache= option and use write-through caching by defaultaliguori1-2/+6
This patch changes the cache= option to accept none, writeback, or writethough to control the host page cache behavior. By default, writethrough caching is now used which internally is implemented by using O_DSYNC to open the disk images. When using -snapshot, writeback is used by default since data integrity it not at all an issue. cache=none has the same behavior as cache=off previously. The later syntax is still supported by now deprecated. I also cleaned up the O_DIRECT implementation to avoid many of the #ifdefs. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5485 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-22Refactor AIO to allow multiple AIO implementationsaliguori1-13/+0
This patch refactors the AIO layer to allow multiple AIO implementations. It's only possible because of the recent signalfd() patch. Right now, the AIO infrastructure is pretty specific to the block raw backend. For other block devices to implement AIO, the qemu_aio_wait function must support registration. This patch introduces a new function, qemu_aio_set_fd_handler, which can be used to register a file descriptor to be called back. qemu_aio_wait() now polls a set of file descriptors registered with this function until one becomes readable or writable. This patch should allow the implementation of alternative AIO backends (via a thread pool or linux-aio) and AIO backends in non-traditional block devices (like NBD). Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5297 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-16block-raw is not a protocolaliguori1-1/+0
The protocol_name "file" was added to the block driver when async IO was introduced. This can be used to select that a file is treated as a raw device instead of probing for the type. However, protocols are not subject to path interpretation which cases qcow2 images with raw base images to not function is the path was specified relatively. The fix is simply to remove the protocol_name from the raw block driver. The proper way to force the use of a raw block format is to use the format= option with -drive. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5233 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-15Use common objects for qemu-img and qemu-nbdaliguori1-25/+16
Right now, we sprinkle #if defined(QEMU_IMG) && defined(QEMU_NBD) all over the code. It's ugly and causes us to have to build multiple object files for linking against qemu and the tools. This patch introduces a new file, qemu-tool.c which contains enough for qemu-img, qemu-nbd, and QEMU to all share the same objects. This also required getting qemu-nbd to be a bit more Windows friendly. I also changed the Windows block-raw to use normal IO instead of overlapping IO since we don't actually do AIO yet on Windows. I changed the various #if 0's to #if WIN32_AIO to make it easier for someone to eventually fix AIO on Windows. After this patch, there are no longer any #ifdef's related to qemu-img and qemu-nbd. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5226 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-10Use signalfd() to work around signal/select racealiguori1-12/+0
This patch introduces signalfd() to work around the signal/select race in checking for AIO completions. For platforms that don't support signalfd(), we emulate it with threads. There was a long discussion about this approach. I don't believe there are any fundamental problems with this approach and I believe eliminating the use of signals is a good thing. I've tested Windows and Linux using Windows and Linux guests. I've also checked for disk IO performance regressions. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5187 c046a42c-6fe2-441c-8c8c-71466251a162
2007-12-24Add "cache" parameter to "-drive" (Laurent Vivier).balrog1-0/+4
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3848 c046a42c-6fe2-441c-8c8c-71466251a162
2007-12-15Split block-raw.c into block-raw-posix.c and block-raw-win32.c, byths1-0/+544
Anthony Liguori. git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3814 c046a42c-6fe2-441c-8c8c-71466251a162