Messages in this thread | | | Date | Sun, 1 Jun 2008 08:23:43 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: sync_file_range(SYNC_FILE_RANGE_WRITE) blocks? |
| |
On Sat, 31 May 2008, Andrew Morton wrote: > On Sat, 31 May 2008 19:44:49 +0100 (BST) Hugh Dickins <hugh@veritas.com> wrote: > > > > All I can say so far is that I find the same as you do: > > SYNC_FILE_RANGE_WRITE (after writing) takes a significant amount of time, > > more than half as long as when you add in SYNC_FILE_RANGE_WAIT_AFTER too. > > > > Which make the sync_file_range call pretty pointless: your usage seems > > perfectly reasonable to me, but somehow we've broken its behaviour. > > I'll be investigating ... > > It will block on disk queue fullness - sysrq-W will tell.
Ah, thank you. What a disappointment, though it's understandable. Doesn't that very severely limit the usefulness of the system call?
I admit the flag isn't called SYNC_FILE_RANGE_WRITE_WITHOUT_WAITING, but I don't suppose Pavel and I are the only ones misled by it.
Hugh
| |