The man page does not say much, but does this mean I have only 396668 used by
programs (used-cached)?
Or shoul I be reading the 2nd line?
[root at ten-212 ~]# free
total used free shared buffers cached
Mem: 7918844 5478820 2440024 0 111684 5082152
-/+ buffers/cache: 284984 7633860
Swap: 9961464 204 9961260
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On Mon, Jul 12, 2010 at 10:15:06AM -0400, Jason Pyeron wrote:> The man page does not say much, but does this mean I have only 396668 used by > programs (used-cached)? > > Or shoul I be reading the 2nd line?Yes, you should be reading the second line.> [root at ten-212 ~]# free > total used free shared buffers cached > Mem: 7918844 5478820 2440024 0 111684 5082152 > -/+ buffers/cache: 284984 7633860 > Swap: 9961464 204 9961260This first line includes all files that are being cached in memory (for faster reading if needed later, for example). That memory will be freed up if needed. The second line doesn't include that cache, so is a better indicator of actual memory use. (And on that first line, "cached" is already part of "used", so your free memory counting the cache is 2440024; it's just provided for informational purposes.) --keith -- kkeller at wombat.san-francisco.ca.us -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 197 bytes Desc: not available URL: <http://lists.centos.org/pipermail/centos/attachments/20100712/98d9babc/attachment.sig>
> -----Original Message----- > From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On > Behalf Of Keith Keller > Sent: Monday, July 12, 2010 10:41 AM > To: CentOS mailing list > Subject: Re: [CentOS] free > > On Mon, Jul 12, 2010 at 10:15:06AM -0400, Jason Pyeron wrote: > > The man page does not say much, but does this mean I have only396668> > used by programs (used-cached)? > > > > Or shoul I be reading the 2nd line? > > Yes, you should be reading the second line. > > > [root at ten-212 ~]# free > > total used free shared buffers > cached > > Mem: 7918844 5478820 2440024 0 111684 > 5082152 > > -/+ buffers/cache: 284984 7633860 > > Swap: 9961464 204 9961260 > > This first line includes all files that are being cached in memory(for> faster reading if needed later, for example). That memory will be > freed up if needed. The second line doesn't include that cache, so is > a better indicator of actual memory use. > > (And on that first line, "cached" is already part of "used", so your > free memory counting the cache is 2440024; it's just provided for > informational purposes.)I did some testing a while back, and my results showed that the -/+ buffers line seemed to be the *Minimum* amount of ram available if the kernel purged it's buffers/cache. Sometimes more is available. (Roughly) The test was: * Turn swap off * Run free * Run 20 instances of a test program that malloc'd 100 megs of ram * Run free, see 2 gigs of ram + orginal amount of ram used. * Kill N number of those programs, which should free up N*100megs * Run free, output of -/+ did not reflect 2gigs - (N*100 megs). I followed up by running enough instances of the test program that I should have run out of memory free said I had, but the programs all started, none were killed. I ran free again got a number pretty close to what I thought should be free. It's a fun test to play with, I assume results vary from kernel to kernel (how aggressive the kernel is cleaning up returned ram). Patrick