On Mon, Nov 10, 2014 at 11:40:23AM -0500, Milosz Tanski wrote: > This patcheset introduces an ability to perform a non-blocking read from > regular files in buffered IO mode. This works by only for those filesystems > that have data in the page cache. > > It does this by introducing new syscalls new syscalls preadv2/pwritev2. These > new syscalls behave like the network sendmsg, recvmsg syscalls that accept an > extra flag argument (RWF_NONBLOCK). > > It's a very common patern today (samba, libuv, etc..) use a large threadpool to > perform buffered IO operations. They submit the work form another thread > that performs network IO and epoll or other threads that perform CPU work. This > leads to increased latency for processing, esp. in the case of data that's > already cached in the page cache. > > With the new interface the applications will now be able to fetch the data in > their network / cpu bound thread(s) and only defer to a threadpool if it's not > there. In our own application (VLDB) we've observed a decrease in latency for > "fast" request by avoiding unnecessary queuing and having to swap out current > tasks in IO bound work threads. Can you write a test (or set of) for fstests that exercises this new functionality? I'm not worried about performance, just correctness.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
