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2008-10-08Fix IO performance regression in sparcaliguori
Replace signalfd with signal handler/pipe. There is no way to interrupt the CPU execution loop when a file descriptor becomes readable. This results in a large performance regression in sparc emulation during bootup. This patch switches us to signal handler/pipe which was originally suggested by Ian Jackson. The signal handler lets us interrupt the CPU emulation loop while the write to a pipe lets us avoid the select/signal race condition. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5451 c046a42c-6fe2-441c-8c8c-71466251a162
2008-10-03Fix warning about missing return valueblueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5405 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-27Make compatfd fallback more robustaliguori
Be more friendly when signalfd() fails, and also add configure checks to detect that syscall(SYS_signalfd) actually works. malc pointed out that some installs do not have /usr/include/linux headers that are in sync with the glibc headers so why SYS_signalfd is defined, it's #defined to _NR_signalfd which is not defined in the /usr/include/linux header. While this is a distro bug, it doesn't hurt to do a more thorough job in detection. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5334 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-26Really fix the BSD build this timealiguori
struct aioinit isn't defined on BSD it appears so we need to guard everything in an #if defined(__linux__). Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5325 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-26Fix build on non-Linux unicesaliguori
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5324 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-26Implement an fd pool to get real AIO with posix-aioaliguori
This patch implements a simple fd pool to allow many AIO requests with posix-aio. The result is significantly improved performance (identical to that reported for linux-aio) for both cache=on and cache=off. The fundamental problem with posix-aio is that it limits itself to one thread per-file descriptor. I don't know why this is, but this patch provides a simple mechanism to work around this (duplicating the file descriptor). This isn't a great solution, but it seems like a reasonable intermediate step between posix-aio and a custom thread-pool to replace it. Ryan Harper will be posting some performance analysis he did comparing posix-aio with fd pooling against linux-aio. The size of the posix-aio thread pool and the fd pool were largely determined by him based on this analysis. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5323 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-26Fix build on FreeBSDaliguori
__GLIBC_PREREQ is defined in such a way that the ! cannot be used in front of it on FreeBSD. Also, -lpthread is not implied by the build and we definitely use it for compatfd support. While at it, I added a default initialization for posix-aio that seems to perform well in our testing. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5322 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-23Relax posix-aio restrictions on newer glibcsaliguori
RedHat 9 shipped glibc 2.3. Modern versions of glibc do not have the aio thread exit issue that the comment references. This patch adjusts the check to only limit aio_init on glibc versions < 2.4. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5304 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-22Refactor AIO to allow multiple AIO implementationsaliguori
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
2008-09-22Do not allow AIO to be inited multiple timesaliguori
This prevents two signalfd() threads from being spawned. This problem was originally spotted by Blue Swirl. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5289 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-16block-raw is not a protocolaliguori
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
2008-09-15Make sure to define fd_open when not on Linuxaliguori
My previous commit broke the build. This was spotted by C.W. Betts. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5231 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-15Use common objects for qemu-img and qemu-nbdaliguori
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
2008-09-11Only build compatfd when using AIO and make sure to always init AIOaliguori
OpenBSD doesn't use AIO so don't try to build compatfd when not using AIO. Also make sure to call qemu_aio_init() from bdrv_init. Everything that uses bdrv calls bdrv_init so it makes sense to init aio from there instead of in every single tool. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5197 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-11Make sure to read siginfo from signalfdaliguori
Otherwise, we'll idle at 100% cpu. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5195 c046a42c-6fe2-441c-8c8c-71466251a162
2008-09-10Use signalfd() to work around signal/select racealiguori
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
2008-08-24Add missing FreeBSD #include (Juergen Lock)blueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5081 c046a42c-6fe2-441c-8c8c-71466251a162
2008-08-15Preliminary OpenBSD host support (based on OpenBSD patches by Todd T. Fries)blueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5012 c046a42c-6fe2-441c-8c8c-71466251a162
2008-08-15Use AIO only if host supports it (based on OpenBSD patches by Todd T. Fries)blueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5010 c046a42c-6fe2-441c-8c8c-71466251a162
2008-07-03Add a parameter to disable host cache, by Laurent Vivier.ths
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4836 c046a42c-6fe2-441c-8c8c-71466251a162
2008-05-28Align file accesses with cache=off (O_DIRECT) (Kevin Wolf, Laurent Vivier)bellard
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4599 c046a42c-6fe2-441c-8c8c-71466251a162
2008-05-07Revert 4367blueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4377 c046a42c-6fe2-441c-8c8c-71466251a162
2008-05-06Align file accesses with cache=off (Kevin Wolf, Laurent Vivier)blueswir1
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4367 c046a42c-6fe2-441c-8c8c-71466251a162
2008-01-06restore original values for ai.aio_threads and ai.aio_numbellard
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3896 c046a42c-6fe2-441c-8c8c-71466251a162
2007-12-24Real SCSI device passthrough (v4), by Laurent Vivier.ths
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3851 c046a42c-6fe2-441c-8c8c-71466251a162
2007-12-24Add "cache" parameter to "-drive" (Laurent Vivier).balrog
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, byths
Anthony Liguori. git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3814 c046a42c-6fe2-441c-8c8c-71466251a162
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