On 12.10.2013, at 13:59, Konstantin Belousov <kostik...@gmail.com> wrote: > > I was not able to reproduce the situation locally. I even tried to start > a lot of threads accessing the mapped regions, to try to outrun the > pagedaemon. The user threads sleep on the disk read, while pagedaemon > has a lot of time to rebalance the queues. It might be a case when SSD > indeed makes a difference. >
With ordinary SATA drive it will take hours just to read 20GB of data from disk because of random access, it will do a lot of seeks and reading speed will be extremely low. SSD dramatically improves reading speed. > Still, I see how this situation could appear. The code, which triggers > OOM, never fires if there is a free space in the swapfile, so the > absense of swap is neccessary condition to trigger the bug. Next, OOM > calculation does not account for a possibility that almost all pages on > the queues can be reused. It just fires if free pages depleted too much > or free target cannot be reached. First I tried with some swap space configured. The OS started to swap out my process after it reached about 20GB which is also not what I expected: what is the reason to swap out regions of read-only mmap()ed files? Is it the expected behaviour? > > Below is the prototype patch, against HEAD. It is not applicable to > stable, please use HEAD kernel for test. Thanks, I will test the patch soon and report the results. _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
