Date: Fri, 11 Feb 2022 01:14:01 +0000 From: tech-lists <tech-lists@zyxst.net> To: questions@freebsd.org Subject: Re: swap/page problem Message-ID: <YgW4WXY93XFlIp23@cloud9.zyxst.net> In-Reply-To: <CAN6yY1s%2BC3ap7rvajujiTqGwQVgkZrHRh6eHnTGHgTsVrfjPcg@mail.gmail.com> References: <CAN6yY1s%2BC3ap7rvajujiTqGwQVgkZrHRh6eHnTGHgTsVrfjPcg@mail.gmail.com>
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--fqIMx3Kuc2tfVDWt Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, Feb 10, 2022 at 02:28:50PM -0800, Kevin Oberman wrote: >During a large build (llvm13), my system ground to a near halt with almost >everything suspended. After several minutes, the system slowly recovered. >When I looked at the messages log, I found 57 kernel messages spread over >3.75 hours, in the form of: >wap_pager: indefinite wait buffer: bufobj: 0, blkno: 862845, size: 20480 > >The block numbers and sizes varied. bufobj was always '0'. I had >significant swap available swap space,as far as I could tell. I have 20GB >of RAM and 24GB of swap. I am running stable 48937-3c6b6246f2f from January >13. > >I know that the LLVM build is huge, but I've not seen this before. What, >exactly, is this message telling me? Am I out of RAM and swap? I couldd add >another 24GB of swap, though it would be on spinning rust, not SSD. I've seen this problem before and came to the conclusion=20 after reading threads on the lists and asking questions that=20 it wasn't a swap problem as primary issue but maybe theres some contention= =20 between processes which affects llvm in particular and makes it eat swap. Also, as you noted, swap doesn't really run out. I use poudriere to build and have parallel jobs set to 1 now=20 with make jobs enabled and the problem doesn't happen. If you're just using the ports tree in the traditional way, try make -j1. If parallel jobs is unset it would use hw.ncpu which here is 8 which would produce the problem you descrive when compiling llvm13. These sysctls are now set: vfs.read_max=3D128 # default 64 - speeds up disk i/o vfs.aio.max_buf_aio=3D8192 vfs.aio.max_aio_queue_per_proc=3D65536 vfs.aio.max_aio_per_proc=3D8192 vfs.aio.max_aio_queue=3D65536 vm.pageout_oom_seq=3D120 vm.pfault_oom_attempts=3D-1 those last two may be especially helpful for your situation. My context here is amd64 i7-4770K (so 8 cpus with HT) clocked to 4.3GHz and the disk used for building poers is SSD wiht 16GB swap (partition). RAM is 32GB --=20 J. --fqIMx3Kuc2tfVDWt Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE8n3tWhxW11Ccvv9/s8o7QhFzNAUFAmIFuFAACgkQs8o7QhFz NAUr1xAAig+npXZB5qXHzpPX8nnO0q5tDTuuXYAP/rM2SwHT2Nkw3p3N5CGpAYw/ 3AscbD3Iq40WZOPIPtI3UgGU8h2hrvr3nt2dBgK4Q3ueIABwoZ3AF0gQ4D9HS1Tj ZUaAd576CBPpAWCo5io7QFAd3dPNjPRxCIEb99z6XCY1KYMKx6QnTvFOY1MKuWOe nazPi2peUUEzYqGFZRkCXCs43+rb2AjcqDQhZlPi3Ff5YLtO2mMGvEx+Yj256p6r XxQ9c+w256MWIsEtjn4FiyeOPWo0lrNm2bVsrrdT0WFRB8vHKZgu0SkKvpR89DmM kv4Q5zsqIh2Vjc+XYipdMnZaCrs60yR2AahR2iADqgVhgNSU+dIxn3kIHXxinpXW jBV81RoCzJwHLroT4VevuzOB0JDjEvUr66H9P78YFZsJRVVKfr/hW5NByONzr/kJ gfmM2/pT1udzwusbmL5obdPwyQtZjsRtGllAZ4eK77oNRZAZkAxgmioKWSqo26Gi nrFPoYuKPvtr5aWbKqD04bUjdMi0R9gIBbS3rJhnomP7wXy+9EAAnLdXR9Vs1ocu PiwVFQebSobrLY7GEyA1fCp5BWIl/YTLGg+UxaS9ZqKXR6DwZHwvaAiM7R4MU+UE oAFmqfbwobW8P2ZP+9OfVGs5o6IQweQ8VYq5nPTdvDuk1KJ3JeQ= =TjLf -----END PGP SIGNATURE----- --fqIMx3Kuc2tfVDWt--
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