zfs-discuss@opensolaris.org
[Top] [All Lists]

[zfs-discuss] Periodic flush

Subject: [zfs-discuss] Periodic flush
From: Bob Friesenhahn
Date: Wed, 26 Mar 2008 21:35:06 -0500 CDT
My application processes thousands of files sequentially, reading 
input files, and outputting new files.  I am using Solaris 10U4. 
While running the application in a verbose mode, I see that it runs 
very fast but pauses about every 7 seconds for a second or two.  This 
is while reading 50MB/second and writing 73MB/second (ARC cache miss 
rate of 87%).  The pause does not occur if the application spends more 
time doing real work.  However, it would be nice if the pause went 
away.

I have tried turning down the ARC size (from 14GB to 10GB) but the 
behavior did not noticeably improve.  The storage device is trained to 
ignore cache flush requests.  According to the Evil Tuning Guide, the 
pause I am seeing is due to a cache flush after the uberblock updates.

It does not seem like a wise choice to disable ZFS cache flushing 
entirely.  Is there a better way other than adding a small delay into 
my application?

Bob
======================================
Bob Friesenhahn
bfriesen@xxxxxxxxxxxxxxxxxxx, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

_______________________________________________
zfs-discuss mailing list
zfs-discuss@xxxxxxxxxxxxxxx
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

<Prev in Thread] Current Thread [Next in Thread>