Guys,
could someone explain me this?
# sysctl hw.realmem
hw.realmem: 2139029504
top line shows:
Mem: 32M Active, 35M Inact, 899M Wired, 8392K Cache,
199M Buf, 58M Free
32+35+899+8+199+58 = 1231MB
Shouldn't that sum to all available ram? Or maybe I'm reading
it wrong?
This machine has indeed 2GB of ram on board and showed in BIOS.
i386 FreeBSD 8.2-PRERELEASE #16: Mon Jan 17 22:28:53 CET 2011
Cheers.
First, don't include 'buf' as isn't a separate set of RAM, it
is only a range
of the virtual address space in the kernel. It used to be
relevant when the
buffer cache was separate from the VM page cache, but now it is
mostly
irrelevant (arguably it should just be dropped from top output).
Thanks for the explanation. So 1231MB - 199MB Buf and we got
about 1GB
of memory instead of 2B.
However, look at what hw.physmem says (and the realmem and
availmem lines in
dmesg). realmem is actually not that useful as it is not a
count of the
amount of memory, but the address of the highest memory page
available. There
can be less memory available than that due to "holes" in the
address space for
PCI memory BARs, etc.
OK, here you go:
# sysctl hw | grep mem
hw.physmem: 2125893632
hw.usermem: 1212100608
hw.realmem: 2139029504
hw.pci.host_mem_start: 2147483648
Humm, you should still have 2GB of RAM then. All the memory you
set aside
for ARC should be counted in the 'wired' count, so I'm not sure
why you see
1GB of RAM rather than 2GB.
For what its worth (seems to be the same values top shows), the
sysctl's
I use to make cacti graphs of memory usage are: (Counts are in pages)
vm.stats.vm.v_page_size
vm.stats.vm.v_wire_count
vm.stats.vm.v_active_count
vm.stats.vm.v_inactive_count
vm.stats.vm.v_cache_count
vm.stats.vm.v_free_count
Using the output of those sysctls I allways get a cacti graph
which at
least very much seems to account for all memory, and has a flat
surface
in a stacked graph.
These sysctls are exactly what top uses. There is also a
'v_page_count'
which is a total count of pages.
So here's additional sysctl output from now:
fbsd# sysctl hw | grep mem
hw.physmem: 2125893632
hw.usermem: 1392594944
hw.realmem: 2139029504
hw.pci.host_mem_start: 2147483648
fbsd# sysctl vm.stats.vm
vm.stats.vm.v_kthreadpages: 0
vm.stats.vm.v_rforkpages: 0
vm.stats.vm.v_vforkpages: 1422927
vm.stats.vm.v_forkpages: 4606557
vm.stats.vm.v_kthreads: 40
vm.stats.vm.v_rforks: 0
vm.stats.vm.v_vforks: 9917
vm.stats.vm.v_forks: 30429
vm.stats.vm.v_interrupt_free_min: 2
vm.stats.vm.v_pageout_free_min: 34
vm.stats.vm.v_cache_max: 27506
vm.stats.vm.v_cache_min: 13753
vm.stats.vm.v_cache_count: 20312
vm.stats.vm.v_inactive_count: 18591
vm.stats.vm.v_inactive_target: 20629
vm.stats.vm.v_active_count: 1096
vm.stats.vm.v_wire_count: 179027
vm.stats.vm.v_free_count: 6193
vm.stats.vm.v_free_min: 3260
vm.stats.vm.v_free_target: 13753
vm.stats.vm.v_free_reserved: 713
vm.stats.vm.v_page_count: 509752
vm.stats.vm.v_page_size: 4096
vm.stats.vm.v_tfree: 196418851
vm.stats.vm.v_pfree: 2837177
vm.stats.vm.v_dfree: 0
vm.stats.vm.v_tcached: 1305893
vm.stats.vm.v_pdpages: 3527455
vm.stats.vm.v_pdwakeups: 187
vm.stats.vm.v_reactivated: 83786
vm.stats.vm.v_intrans: 3053
vm.stats.vm.v_vnodepgsout: 134384
vm.stats.vm.v_vnodepgsin: 29213
vm.stats.vm.v_vnodeout: 96249
vm.stats.vm.v_vnodein: 29213
vm.stats.vm.v_swappgsout: 19730
vm.stats.vm.v_swappgsin: 8573
vm.stats.vm.v_swapout: 5287
vm.stats.vm.v_swapin: 2975
vm.stats.vm.v_ozfod: 83338
vm.stats.vm.v_zfod: 2462557
vm.stats.vm.v_cow_optim: 330
vm.stats.vm.v_cow_faults: 1239253
vm.stats.vm.v_vm_faults: 5898471
fbsd# sysctl vm.vmtotal
vm.vmtotal:
System wide totals computed every five seconds: (values in
kilobytes)
===============================================
Processes: (RUNQ: 1 Disk Wait: 0 Page Wait: 0
Sleep: 60)
Virtual Memory: (Total: 4971660K Active: 699312K)
Real Memory: (Total: 540776K Active: 29756K)
Shared Virtual Memory: (Total: 41148K Active: 19468K)
Shared Real Memory: (Total: 4964K Active: 3048K)
Free Memory Pages: 105308K
/usr/bin/top line: Mem: 4664K Active, 73M Inact, 700M Wired, 79M
Cache, 199M Buf, 23M Free
Sum (Without Buf): 879,5 MB
So what are we looking at? Wrong sysctls/top output or maybe
actually FreeBSD doesn't use all available RAM for some reason?
Could it be hardware problem? Maybe I should provide some
additional
data?
Does the behaviour become more expected if you remove ZFS from the
picture? Please try this (yes really).
About an hour ago I had to hard reset this machine because it stopped
responding (bu still gived ping response) after massive slowdown seen
by SAMBA users.
Now top shows following:
Mem: 78M Active, 83M Inact, 639M Wired, 120K Cache, 199M Buf, 1139M Free.
What I am afraid is that this PC slowly eats own memory and finally
starved itself to death, because it happened second time in 2 weeks,
and it seems that rebuilding world+kernel Mon Jan 17 22:28:53 CET 2011
could be the cause. For some strange reason I believe that Jeremy
Chadwick could be right pointing ZFS. Way this machine stops
responding without any info in logs makes me believe that it has
simply lost ability to I/O to HDD (system is ZFS-only).
Day 2 after reboot:
Mem: 100M Active, 415M Inact, 969M Wired, 83M Cache, 199M Buf, 21M Free
Sum: 1588MB
1/4 of total RAM disappeared already.
Anyone knows what possibly happening here or maybe I should hire some
voodoo shaman to expel memory-eating-ghost from the machine ;)?
--
Bartosz Stec
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