tops shows 0k for buffers and shared?

Macros73 · n00b Joined: 04 Jun 2002 Posts: 25

The 'top' command displays the following output, which doesn't make much sense to me.

Shared should not list 0k, nor should buff, should it?

Any ideas? This is a fresh install of Gentoo that I created over the weekend from the stage3 tarball.

mem: 256044K av, 195908K used, 60136K free, 0K shrd, 0K buff
Swap: 530136K av, 0K used, 530136K free 83464K cached

lx · Posted: Tue Jun 04, 2002 11:21 pm Post subject:

My shared is also 0k my buffers is used.

cat /proc/meminfo gives:

Utoxin · Posted: Tue Jun 04, 2002 11:27 pm Post subject:

It's perfectly reasonable for those to be empty. It just means that the kernel does'n believe anything needed buffered. (I forget whether buffer is for read or write.)

And my system never has anything in shared. Not sure why, but it doesn't. So you're fine.

Macros73 · n00b Joined: 04 Jun 2002 Posts: 25

It does concern me that MemShared is 0kB. Isn't Linux (and UNIX in general) supposed to share portions of common code between applications, which is, I had thought, reflected in the MemShared field? IE, it loads only one copy of that code into memory and shares it between the various apps?

A Buffers of 0kB also worries me, but that might be due to my using XFS on my / filesystem. Perhaps buffers used by XFS aren't being reported back to the OS as expected.

cat /proc/meminfo

total: used: free: shared: buffers: cached:
Mem: 262189056 238166016 24023040 0 0 88571904
Swap: 542859264 0 542859264
MemTotal: 256044 kB
MemFree: 23460 kB
MemShared: 0 kB
Buffers: 0 kB
Cached: 86496 kB
SwapCached: 0 kB
Active: 137940 kB
Inact_dirty: 18260 kB
Inact_clean: 46400 kB
Inact_target: 40520 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 256044 kB
LowFree: 23460 kB
SwapTotal: 530136 kB
SwapFree: 530136 kB

Macros73 · n00b Joined: 04 Jun 2002 Posts: 25

According to the Linux FAQ, processes in 2.4 do indeed still share memory.

However, due to changes in the virtual memory layer, it is too costly to tally up all that shared memory. Therefore, in order not to break userland tools, MemShared in /proc/info was set to 0kB.

Anyone know of a tool that will go through and pull out such stats, or is that information completely unavailable under Linux kernel 2.4?

Macros73 · n00b Joined: 04 Jun 2002 Posts: 25

ipcs appears to provide some stats on shared memory usage..guess I'll work from there. Additional tips more than welcome.

Utoxin · Posted: Wed Jun 05, 2002 12:45 am Post subject:

Hmmmm. I'm running XFS as well, so maybe you're right about the buffer thing.

*blinks as he absently checks top*

Never mind. My buffer is in use right now. Not much, but it is. (Just over 1 meg).

And the shared memory thing makes sense. If you look at the process list in top, it does list memory as shared for most processes.

Macros73 · n00b Joined: 04 Jun 2002 Posts: 25

Hmm. My buffers are still not in use and the system has been up for a few days. Any ideas? How can I check the configuration settings for disk buffers?

Utoxin · Posted: Wed Jun 05, 2002 6:18 pm Post subject:

As far as I know, there is no configuration. It's handled automagically by the kernel. I /do/ remember that mine were empty for quite some time.