Visit Jeremy's Blog.
Go Back > Forums > Linux Forums > Linux - Software
User Name
Linux - Software This forum is for Software issues.
Having a problem installing a new program? Want to know which application is best for the job? Post your question in this forum.


  Search this Thread
Old 11-03-2004, 11:09 PM   #1
LQ Newbie
Registered: Nov 2004
Posts: 1

Rep: Reputation: 0
Do any kernels support a multi-gigabyte buffer cache?


I have a system with 4.5G of ram.

I noticed (using 'free') that the system buffer cache
was limited to about 820M.

The server will hold up to 12G of ram.

I use kernel 2.4.20-31.9bigmem.

Do any kernels support a multi-gigabyte buffer cache?


Old 11-04-2004, 01:34 AM   #2
Senior Member
Registered: Jun 2004
Posts: 2,553

Rep: Reputation: 53

as far as i know Linux will automatically try to uses ALL free ram for buffer cache, and automatically makes the cache smaller when programs need more memory.
but low usage was a problem with those older kernels
i would migrate to 2.6 kernel where lots of issues with highmem have been addressed
2.6 kernel supports larger pages up to 2/4M and page table entries can now exist in highmem
removing the old 1Gb constraint for pte's allowing better use of more memory
has larger table lookaside buffer that can actually stay cached because pte's are moved out of lowmem
and since buffer cache like you said is ultimately about block device reads the kernel you are using had to route all block device i/o through the first 1Gb kernel set aside one locked read at a time and then bounce to a highmem address.
newer kernel block device drivers support direct highmem DMA and more finer grained locking and i bet this will fix what you are seeing and speed you up alot. and eliminate that waste of memory.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
buffer/cache variable for free command... audibel Linux - Software 3 12-14-2007 03:54 PM
file buffer cache jwstric2 Linux - General 2 06-30-2004 05:25 PM
Multi-boot Windows, Debian with several kernels loopyzort Linux - Newbie 12 06-03-2004 07:32 PM
Support Gigabyte Ga-8IK1100? Zoltam Linux - General 0 07-08-2003 03:42 AM
File buffer cache structure dserban Linux - General 0 04-20-2001 05:20 PM > Forums > Linux Forums > Linux - Software

All times are GMT -5. The time now is 06:22 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration