Date: Wed, 26 Jan 2011 19:21:42 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Bartosz Stec <bartosz.stec@it4pro.pl> Cc: freebsd-stable@freebsd.org Subject: Re: top shows only part of available physmem Message-ID: <20110127032142.GA19946@icarus.home.lan> In-Reply-To: <4D40C355.6070306@it4pro.pl> References: <4D401192.3030400@it4pro.pl> <201101261235.56856.jhb@freebsd.org> <20110126180402.GA17271@tolstoy.tols.org> <201101261344.50756.jhb@freebsd.org> <4D40C355.6070306@it4pro.pl>
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On Thu, Jan 27, 2011 at 01:59:01AM +0100, Bartosz Stec wrote: > W dniu 2011-01-26 19:44, John Baldwin pisze: > >On Wednesday, January 26, 2011 1:04:02 pm Marco van Tol wrote: > >>On Wed, Jan 26, 2011 at 12:35:56PM -0500, John Baldwin wrote: > >>>On Wednesday, January 26, 2011 8:20:28 am Bartosz Stec wrote: > >>>>W dniu 2011-01-26 14:06, John Baldwin pisze: > >>>>>On Wednesday, January 26, 2011 7:20:34 am Bartosz Stec wrote: > >>>>>>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). -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP 4BD6C0CB |
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