On 12/11/12 08:29, Jens Axboe wrote:
You are right, blkid likely wont be done by then, so it's still down to timing whether it'll help or not. This is pretty annoying. This issue is due to the file being opened for write. But unfortunately we cannot open for read always, as fcntl() wont allow change of file access mode flags. So how about the below. Basically DON'T close the fd, defer that until we really close the file. This will keep one extra fd open until the original is closed, but I don't see that as being an issue.
This patch seems to be working just fine. I have reproduced the case where it uses the shadow_fd field, but blkid doesn't run and the page cache entries don't get loaded, and in my initial tests with dm-zero, it looks like the bimodal performance distribution is gone.
Thanks! Ken -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
