Date: Sat, 3 Jul 2021 02:56:40 +0300 From: Vitaliy Gusev <gusev.vitaliy@gmail.com> To: freebsd-hackers@freebsd.org Cc: Konstantin Belousov <kib@FreeBSD.org> Subject: madvise(MADV_FREE) doesn't work in some cases? Message-ID: <D5749BDF-36B5-4AE9-A75F-2A702DF71F8C@gmail.com>
next in thread | raw e-mail | index | archive | help
[-- Attachment #1 --] Hi, I came across not expected behaviour with madvise() in FreeBSD. Attached test program mmapfork does: mmap, fork, touch memory and then madvise(MADV_FREE). Expected behaviour - one process can allocate memory (lazy allocation) while system is freeing previously allocated memory for a second process. Current behaviour - system kills one process with message in dmesg: pid 31314 (mmapfork), jid 0, uid 1001, was killed: out of swap space Running this test in Linux or illumos shows expected behaviour with a little difference in illumos - it frees memory almost immediately, w/o needs lack of memory in a system. If use MADV_NOTNEED - no changes. If modify program and do not do fork(), but run two instances - that shows expected behaviour. To reproduce just disable swap, and run program with argument as 1/2 RAM on a system. For instance, command below will try run and use ~ 2GB area twice. [vetal@bsdev ~]$ ./mmapfork 2000 Testing program is attached. Note, during testing I disabled swap on all systems: Linux, illumos and FreeBSD. Does it mean madvise() doesn't work well in FreeBSD or test does something wrong? Thanks, Vitaliy Gusev [-- Attachment #2 --] --Apple-Mail=_1525D0A7-8A3B-4A8C-9910-463C30219109--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?D5749BDF-36B5-4AE9-A75F-2A702DF71F8C>