block and fetch size for ULTRIX on DECstation 5000/200

Article View: comp.sys.dec

Article #187

#187

From: Paul Wilson
Date: Wed, 29 Jul 1992 15:30

22 lines
1328 bytes

I'm getting some unexpectedly good performance numbers with some
software I'm running, which looks like it's because file system
block reads are faster than virtual memory pageins.

Can anybody tell me offhand what's going on?  I'm reading 4K
blocks from files, and it's unexpectedly fast.  My guess is
that the filesystem is actually fetching 8K blocks, where the
VM system is fetching 4K pages, or maybe the file system is
doing one-block lookahead prefetching.

We're using ULTRIX 4.1.

Any clarification would be appreciated.

Thanks,

   Paul
-- 
| Paul R. Wilson                                    wilson@cs.utexas.edu      |
| U. of Texas Computer Sciences Dept.               voice: (512) 471-9555     |
| Taylor Hall 2.124, Austin, TX 78712-1188          fax:   (512) 471-8885     |
| "Inertia makes the world go 'round."                                        |

Technical Details

Message-ID: <l7deddINNt72@boogie.cs.utexas.edu>

Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!cs.utexas.edu!news

Show Full Headers

Complete Article Headers

Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!cs.utexas.edu!news
From: wilson@cs.utexas.edu (Paul Wilson)
Newsgroups: comp.sys.dec
Subject: block and fetch size for ULTRIX on DECstation 5000/200
Date: 29 Jul 1992 10:30:53 -0500
Organization: CS Dept, University of Texas at Austin
Lines: 22
Message-ID: <l7deddINNt72@boogie.cs.utexas.edu>
NNTP-Posting-Host: boogie.cs.utexas.edu
Summary: why is file system faster than VM?