Comments on: Memory Management

By: Memory « Oracle Scratchpad

Memory « Oracle Scratchpad — Wed, 23 Jun 2010 19:35:06 +0000

[...] is a topic I’ve raised in the past – but it seems appropriate to post another link to Christo Kutrovsky’s presentation and [...]

By: Jonathan Lewis

Jonathan Lewis — Mon, 21 Sep 2009 14:34:12 +0000

Chen,

I’ve just been prompted to search for this page and thought I’d add in the comment that you’re probably talking about the tcp transmit and receive buffers (actual names vary across flavours of UNIX) that tend to be sized somewhere between 32KB and 1MB each. (Correct me if I’m wrong).

1MB doesn’t sound like much, but with 2 directions and 2,000 users that’s a (possibly surprising) chunk 4GB just disappeared.

By: prodlife

prodlife — Thu, 20 Dec 2007 18:04:12 +0000

OS memory is also used for the network devices. If you have many concurrent connections, the TCP queues may account for a significant portion of OS memory usage.

By: Flado

Flado — Thu, 20 Dec 2007 16:01:54 +0000

I went through some sizing “exercises” (of a large production Oracle 9.2 OLTP database) under AIX 5L this year and if I felt inclined to formulate ROTs, that would be mine for AIX 5L:
Use Concurrent I/O for the datafiles (>= DirectIO), set lru_file_repage to 0 (to protect computational pages), put SGA in 16MB-pages (to both reduce the page tables’s size and pin SGA into physical memory), and leave PGA in non-pinned memory to allow unused but allocated PGA memory to get paged out. Keep an eye on the memory pinned by the OS – it often turns out to be way more than 20%. Measure and monitor.

But I don’t like rules of thumb ;-)

Flado