On Thu, 20 Jun 2013, Jeff Roberson wrote: > On Wed, 19 Jun 2013, Zbyszek Bodek wrote: > >> Hello, >> >> I've been trying to compile the kernel on my ARMv7 platform using the >> sources from the current FreeBSD HEAD. >> >> make buildkernel <.....> -j5 >> >> 1/2 builds fails in the way described below: >> -------------------------------------------------------------------------- >> ing-include-dirs -fdiagnostics-show-option -nostdinc -I. >> -I/root/src/freebsd-arm-superpages/sys >> -I/root/src/freebsd-arm-superpages/sys/contrib/altq >> -I/root/src/freebsd-arm-superpages/sys/contrib/libfdt -D_KERNEL >> -DHAVE_KERNEL_OPTION_HEADERS -include opt_global.h -fno-common >> -finline-limit=8000 --param inline-unit-growth=100 --param >> large-function-growth=1000 -mno-thumb-interwork -ffreestanding -Werror >> /root/src/freebsd-arm-superpages/sys/ufs/ffs/ffs_snapshot.c >> Cannot fork: Cannot allocate memory >> *** [ffs_snapshot.o] Error code 2 >> 1 error >> *** [buildkernel] Error code 2 >> 1 error >> *** [buildkernel] Error code 2 >> 1 error >> 5487.888u 481.569s 7:35.65 1310.0% 1443+167k 1741+5388io 221pf+0w >> -------------------------------------------------------------------------- >> >> The warning from std err is: >> -------------------------------------------------------------------------- >> vm_thread_new: kstack allocation failed >> vm_thread_new: kstack allocation failed >> -------------------------------------------------------------------------- >> >> I was trying to find out which commit is causing this (because I was >> previously working on some older revision) and using bisect I got to: >> >> -------------------------------------------------------------------------- >> Author: jeff <jeff_at_FreeBSD.org> >> Date: Tue Jun 18 04:50:20 2013 +0000 >> >> Refine UMA bucket allocation to reduce space consumption and improve >> performance. >> >> - Always free to the alloc bucket if there is space. This gives LIFO >> allocation order to improve hot-cache performance. This also allows >> for zones with a single bucket per-cpu rather than a pair if the >> entire >> working set fits in one bucket. >> - Enable per-cpu caches of buckets. To prevent recursive bucket >> allocation one bucket zone still has per-cpu caches disabled. >> - Pick the initial bucket size based on a table driven maximum size >> per-bucket rather than the number of items per-page. This gives >> more sane initial sizes. >> - Only grow the bucket size when we face contention on the zone >> lock, this >> causes bucket sizes to grow more slowly. >> - Adjust the number of items per-bucket to account for the header >> space. >> This packs the buckets more efficiently per-page while making them >> not quite powers of two. >> - Eliminate the per-zone free bucket list. Always return buckets back >> to the bucket zone. This ensures that as zones grow into larger >> bucket sizes they eventually discard the smaller sizes. It persists >> fewer buckets in the system. The locking is slightly trickier. >> - Only switch buckets in zalloc, not zfree, this eliminates >> pathological >> cases where we ping-pong between two buckets. >> - Ensure that the thread that fills a new bucket gets to allocate from >> it to give a better upper bound on allocation time. >> >> Sponsored by: EMC / Isilon Storage Division >> -------------------------------------------------------------------------- >> >> I checked this several times and this commits seems to be causing this. > > Can you tell me how many cores and how much memory you have? And paste the > output of vmstat -z when you see this error. > > You can try changing bucket_select() at line 339 in uma_core.c to read: > > static int > bucket_select(int size) > { > return (MAX(PAGE_SIZE / size, 1)); > } > > This will approximate the old bucket sizing behavior. Just to add some more information; On my machine with 16GB of ram the handful of recent UMA commits save about 20MB of kmem on boot. There are 30% fewer buckets allocated. And all of the malloc zones have similar amounts of cached space. Actually the page size malloc bucket is taking up much less space. I don't know if the problem is unique to arm but I have tested x86 limited to 512MB of ram without trouble. I will need the stats I mentioned before to understand what has happened. Jeff > > Thanks, > Jeff > >> >> Does anyone observe similar behavior or have a solution? >> >> Best regards >> Zbyszek Bodek >> >Received on Thu Jun 20 2013 - 22:03:29 UTC
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