PR/53124 CVS commit: src/sys/uvm

["Jaromir Dolecek" <jdolecek%netbsd.org@localhost>]

The following reply was made to PR kern/53124; it has been noted by GNATS.

From: "Jaromir Dolecek" <jdolecek%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/53124 CVS commit: src/sys/uvm
Date: Sat, 19 May 2018 15:18:02 +0000

 Module Name:	src
 Committed By:	jdolecek
 Date:		Sat May 19 15:18:02 UTC 2018
 
 Modified Files:
 	src/sys/uvm: uvm_readahead.c
 
 Log Message:
 adjust heuristics for read-ahead to skip the full read-ahead when last page of
 the range is already cached; this speeds up I/O from cache, since it avoids
 the lookup and allocation overhead
 
 on my system I observed 4.5% - 15% improvement for cached I/O - from 2.2 GB/s to
 2.3 GB/s for cached reads using non-direct UBC, and from 5.6 GB/s to 6.5 GB/s
 for UBC using direct map
 
 part of PR kern/53124
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.9 -r1.10 src/sys/uvm/uvm_readahead.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.