On Tue, Jan 06, 2015 at 12:47:14AM -0800, Andrew Morton wrote: > > progress, which is a bit frustrating. > > I took a look at pread2() as well and I have two main issues: > > - The patchset includes a pwrite2() syscall which has nothing to do > with nonblocking reads and which was poorly described and had little > justification for inclusion.
It allows to do O_SYNC writes on a per-I/O basis. This is very useful for file servers (smb, cifs) as well as storage target devices. Note: that part was my addition, and the complaint about lacking description ever made it to me. Can you point to the relevant questions? > - We've talked for years about implementing this via fincore+pread > and at least two fincore implementations are floating about. Now > along comes pread2() which does it all in one hit. > > Which approach is best? I expect fincore+pread is simpler, more > flexible and more maintainable. But pread2() will have lower CPU > consumption and lower average-case latency. fincore+pread is inherently racy and thus entirely unsuitable for the use case of a non-blockign main thread. Nevermind that the pread2 path is way simpler than any of the proposed fincore patches. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
