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readahead.2: Tweaks to Phillip Susi;s patch 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk 2014-03-15 10:02:57 +01:00
parent afc9c3a076
commit 6a7c9c0a7f
1 changed files with 12 additions and 7 deletions
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19
man2/readahead.2
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@ -25,7 +25,7 @@
.\" 2004-05-40 Created by Michael Kerrisk <mtk.manpages@gmail.com>
.\" 2004-10-05 aeb, minor correction
.\"
.TH READAHEAD 2 2013-04-01 "Linux" "Linux Programmer's Manual"
.TH READAHEAD 2 2014-03-15 "Linux" "Linux Programmer's Manual"
.SH NAME
readahead \- initiate file readahead into page cache
.SH SYNOPSIS
@ -37,8 +37,11 @@ readahead \- initiate file readahead into page cache
.fi
.SH DESCRIPTION
.BR readahead ()
initates readahead on a file so that subsequent reads from that file will
hopefully be satisfied from the cache, and not block on disk I/O.
initiates readahead on a file so that subsequent reads from that file will,
be satisfied from the cache, and not block on disk I/O
(assuming the readahead was initiated early enough and that other activity
on the system did not in the meantime flush pages from the cache).
The
.I fd
argument is a file descriptor identifying the file which is
@ -93,10 +96,12 @@ the calling signature for this system call differs,
for the reasons described in
.BR syscall (2).
The call attempts to schedule the reads in the background and return
immediately, however it may block while reading filesystem metadata
in order to locate where the blocks requested are. This occurs frequently
with ext[234] on large files using indirect blocks instead of extents,
.BR readahead ()
attempts to schedule the reads in the background and return immediately.
However, it may block while it reads the filesystem metadata needed
to locate the requested blocks.
This occurs frequently with ext[234] on large files
using indirect blocks instead of extents,
giving the appearence that the call blocks until the requested data has
been read.
.SH SEE ALSO