<<On Fri, 12 Sep 2025 21:35:26 -0400, Garrett Wollman <woll...@bimajority.org> said:
> The point being that the ARC is supposed to respond to backpressure > long before memory runs out. And again, we're talking about a system > with 100 GiB of outright FREE physical memory. There's no possible > way that can be fully allocated in less than 5 minutes -- the NICs > aren't that fast and the servers aren't doing anything else. The past couple of nights we've had failures of other NFS servers (same FreeBSD build, different hardware, different clients, different data). The most recent one, unlike the one I started this thread with, didn't get so far as to invoke the OOM killer -- it seems to have been stuck in arc_wait_for_eviction(). I wasn't in a position to get a backtrace, so I can't tell if this was the call from arc_get_data_impl() (which is called for every block allocated but normally just returns immediately) or the one from arc_lowmem() (which is ultimately called from the vm_lowmem event handler when the system is really out of memory). As with previous failures, this one was with plenty of physical memory seemingly available (20 GiB out of 96 GiB). Separate swap partition, of course, and after 34 minutes memory allocation is pretty much back to where it was before the crash. -GAWollman
