On Tue, 31 May 2022 at 12:34, Sam Li <[email protected]> wrote: > > Stefan Hajnoczi <[email protected]> 于2022年5月31日周二 19:31写道： > > > > On Tue, May 31, 2022 at 06:50:11PM +0800, Sam Li wrote: > > > Linux recently added a new io_uring(7) optimization API that QEMU > > > doesn't take advantage of yet. The liburing library that QEMU uses > > > has added a corresponding new API calling io_uring_register_ring_fd(). > > > When this API is called after creating the ring, the io_uring_submit() > > > library function passes a flag to the io_uring_enter(2) syscall > > > allowing it to skip the ring file descriptor fdget()/fdput() > > > operations. This saves some CPU cycles. > > > > > > Signed-off-by: Sam Li <[email protected]> > > > --- > > > block/io_uring.c | 12 +++++++++++- > > > meson.build | 1 + > > > 2 files changed, 12 insertions(+), 1 deletion(-) > > > > Thanks, applied to my block tree: > > https://gitlab.com/stefanha/qemu/commits/block > > > > Great! Sorry about the mistake before. I'm flushed.
Don't worry, it's easy for #ifdef issues to slip through. Two techniques for testing #ifdefs: 1. To check whether compilation works both when the macro is defined and also when it is undefined, edit the #ifdef to force the compiler to take or not take the #ifdef. For example, if #ifdef FOO is compiled but you want to test the case where FOO is undefined, temporarily change it to #ifdef FOOX. 2. Add "#error foo" inside the #ifdef to test whether the compiler is parsing the code. If you expect the #ifdef to be compiled but there is no compilation error then there is a problem. Stefan
