Re: LowFree pattern

[Bill Davidsen]

Adayadil Thomas wrote:
> > What problem did you see that you traced to LowFree?
> >     
>
> I have set this device as a bridge. Higher latency and low throughput seem
> to be related to LowFree. There are also packet drops at the interface
> when LowFree is too low.
>
> I have another device which has 4G RAM split into 900M LowMem and
> the rest as HighMem. In that case also, LowMem goes to a low level, say 8M
> and although HighMem has ~2G free, the system gives OOPS (related to
> page_alloc failures)
> when acting as a bridge (passing packets).
>
>   
Then /proc/sys/vm tuning may help.
> On Wed, Sep 2, 2009 at 3:22 PM, Bill Davidsen<davidsen@xxxxxxx> wrote:
>   
> > Adayadil Thomas wrote:
> >     
> > > Greetings.
> > >
> > > I am running a centos linux with 2.6.20 version kernel. The system has
> > > 1G of RAM.
> > >
> > > As time goes by the LowFree becomes really low. Right now it shows
> > > 137M .. but it goes as low as 8M or so
> > >
> > > The command -
> > > echo 3 > /proc/sys/vm/drop_caches
> > > brings back the LowFree to way up high.
> > >
> > > The question I have is whether the system by itself release the cache
> > > (drop cache) automatically
> > > to maintain a reasonable LowFree?
> > > Is this configurable?
> > >
> > >       
> > You can change the parameters in /rpoc/sys/vm if you wish, but what makes
> > you think this is needed? Cache is dropped as memory is needed, and
> > drop_cache in general is a good way to slow the system.
> >
> >     
> > > Any information or help is much appreciated.
> > >
> > >       
> > What problem did you see that you traced to LowFree?
> >
> >     
> > > cat /proc/meminfo
> > > MemTotal:      1034788 kB
> > > MemFree:        138240 kB
> > > Buffers:         99260 kB
> > > Cached:         177776 kB
> > > SwapCached:      51740 kB
> > > Active:         605172 kB
> > > Inactive:       113572 kB
> > > HighTotal:      130720 kB
> > > HighFree:          252 kB
> > > LowTotal:       904068 kB
> > > LowFree:        137988 kB
> > > SwapTotal:     1048568 kB
> > > SwapFree:       976332 kB
> > > Dirty:             380 kB
> > > Writeback:           0 kB
> > > AnonPages:      441348 kB
> > > Mapped:          15540 kB
> > > Slab:           146088 kB
> > > SReclaimable:   104288 kB
> > > SUnreclaim:      41800 kB
> > > PageTables:       1596 kB
> > > NFS_Unstable:        0 kB
> > > Bounce:              0 kB
> > > CommitLimit:   1565960 kB
> > > Committed_AS:   590576 kB
> > > VmallocTotal:   114680 kB
> > > VmallocUsed:     15052 kB
> > > VmallocChunk:    99348 kB
> > >       


--
bill davidsen <davidsen@xxxxxxx>
 CTO TMR Associates, Inc

"Now we have another quarterback besides Kurt Warner telling us during postgame
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