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Re: confused with memory usage, sar, top, free, vmstat



Good Advice!!!! :-)

ESG

2010/3/18 hike <mh1272 gmail com>

> if you boss thinks that more memory is needed, don't disabuse him of that
> idea--buy more memory!!!
>
> i make it a practice to never refuse more resources!
>
> the resource your boss will buy today may be the resource that is needed
> tomorrow but he will not approve.
>
>
>
>
> On Wed, Mar 17, 2010 at 8:28 AM, ESGLinux <esggrupos gmail com> wrote:
>
> > Hi Matthew, thanks for your answer.
> >
> > so, when this tools say that the memused is 3,4G this is true but with
> the
> > detail that the amount allocated in buffers y cache are avaliable to use,
> > isnt it?
> >
> > one finally doubt is about swap, Why I have an 8% of swap if I really
> have
> > a
> > lot of free mem?
> >
> > Well, with this I think I can tell my boss that we don´t need to buy more
> > mem ;-)
> >
> > Greetings,
> >
> > ESG
> >
> >
> > 2010/3/17 Stainforth, Matthew (SD/DS) <Matthew Stainforth gnb ca>
> >
> > > Is is fine.  The output of sar, free, top, and vmstat are all agreeing
> > that
> > > you have about 3.4GB mem used (~82%) with about 750MB free.
> > >
> > > The kbbuffers and kbcached from sar agrees with buffers (.48 GB) and
> > cached
> > > (.56 GB) from free.  The buff and cached from vmstat also agrees.
> > >
> > > Now if you look at the -/+ buffers/cache line from free, you will see
> > that
> > > you really only have 2.36GB used and 1.78GB free if you don't count
> > buffers
> > > and cache.  2.36GB + .48GB + .56GB = 3.4GB used.
> > >
> > > So you have about a gig of memory tied up in buffers and cache that
> could
> > > be freed if needed by the system.
> > >
> > > Further, you only have 40MB (8%) of swap used.  If you were starved for
> > > memory this would be higher and your cache and buffers would be lower.
> > >
> > > > -----Original Message-----
> > > > From: redhat-list-bounces redhat com [mailto:redhat-list-
> > > > bounces redhat com] On Behalf Of ESGLinux
> > > > Sent: Wednesday, March 17, 2010 5:44 AM
> > > > To: General Red Hat Linux discussion list
> > > > Subject: confused with memory usage, sar, top, free, vmstat
> > > >
> > > > Hi all,
> > > >
> > > > I have a server that I think is having problems with memory usage but
> > > > when I
> > > > try to analize with different tools I´m not sure if I having problems
> > > > with
> > > > it
> > > >
> > > > If I run sar -r:
> > > > ...
> > > > 04:50:01    kbmemfree kbmemused  %memused kbbuffers  kbcached
> kbswpfree
> > > > kbswpused  %swpused  kbswpcad
> > > > 09:05:01       748036   3401232             81,97    448672    599232
> > > > 3768868    327664      8,00     40456
> > > > 09:10:01       749596   3399672            81,93    480028    560856
> > > > 3768868    327664      8,00     40456
> > > > 09:15:01       749020   3400248            81,95    481144    559740
> > > > 3768868    327664      8,00     40456
> > > > 09:20:01       749516   3399752            81,94    481812    559332
> > > > 3768868    327664      8,00     40456
> > > > 09:25:01       749676   3399592            81,93    481928    559216
> > > > 3768868    327664      8,00     40456
> > > > ...
> > > >
> > > > free
> > > >                       total       used       free           shared
> > > >  buffers     cached
> > > > Mem:       4149268    3407624     741644          0     481084
> > > > 566300
> > > > -/+ buffers/cache:    2360240    1789028
> > > > Swap:      4096532     327664    3768868
> > > >
> > > > vmstat 1
> > > > procs -----------memory---------- ---swap-- -----io---- --system--
> > > > ----cpu----
> > > >  r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us
> > > > sy id
> > > > wa
> > > >  0  0 327664 741412 481444 566200    1    1    10    56    0     2  2
> > > > 1 96
> > > >  1
> > > >  0  0 327664 741412 481452 566192    0    0     0    24 1017   880  1
> > > > 0 99
> > > >  1
> > > >  0  0 327664 741428 481460 566184    0    0     0    60 1012   812  0
> > > > 0 99
> > > >  1
> > > >  0  0 327664 741428 481460 566184    0    0     0     0 1008   835  0
> > > > 0 100
> > > >  0
> > > >  2  1 327664 741428 481464 566180    0    0     0    12 1020   859  0
> > > > 0 100
> > > >  0
> > > >
> > > > top -b -d 1 -n 1
> > > > top - 09:37:02 up 141 days, 20:15,  1 user,  load average: 0.00,
> 0.02,
> > > > 0.03
> > > > Tasks: 115 total,   1 running, 114 sleeping,   0 stopped,   0 zombie
> > > > Cpu(s):  1.6% us,  0.6% sy,  0.2% ni, 96.4% id,  1.2% wa,  0.0% hi,
> > > > 0.0% si
> > > > Mem:   4149268k total,  3408280k used,   740988k free,   481752k
> > > > buffers
> > > > Swap:  4096532k total,   327664k used,  3768868k free,   566152k
> cached
> > > >
> > > > I have read that linux try to allocate all the RAM memory, so the
> real
> > > > free
> > > > memory is the free + buffers/cache, is it true? if so, the %memused
> > > > shown by
> > > > sar -r is not true?
> > > >
> > > > Can anybody give a light to understand this (docs, tools...)? with
> the
> > > > commands I have post do you think that I´m having problems with the
> > > > memory
> > > > or can I be calm?
> > > >
> > > > Thanks in advance
> > > >
> > > > ESG
> > > > --
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