Hello all..
Using dtrace on solaris 10, i could investigate a performance issue with the
sincronization of some files on a ZFS filesystem. I have started the follow
rsync command (inside a gnome-terminal):
/opt/sfw/bin/rsync -av -e ssh user@IP:/DirA/DirB .
The current directory(.), was a ZFS pool with two SATA discs (mirror)...
The performance was terrible. After some tests with raid0, raid1, non-SATA
discs, and using DTrace, i have realized that the problem was the
"gnome-terminal". Basically the "-v" switch.
I'm preparing a document to post on my blog
(www.posix.brte.com.br/blog), but i want your insights about:
1- How the "-v" switch works? I mean, the rsync "waits" for
the terminal is "ready" to display text (stays blocked)?
2- The system was idle (98%), and the 1,5% was running gnome-terminal.. the
iostat did show me 1M per 10 minutes (more or less). Could the driver (pipe) be
the problem?
I want the opinion of the developers to know if the "rsync" can be
the "problem" (it was waiting). Or i can continue my investigation on
kernel (driver) and gnome-terminal?
How that conversation (pipe) works?
If i execute the same comand line on a console, or ssh session, everything
works fine. If i execute almost the same command (without the "-v"
option) and put the process to backgound ("&"), everything works
fine (not so fast, but a good performance).
Thanks very much for your time.
MSL
Hi, On Nov/30/2006, diversos wrote:> 1- How the "-v" switch works? I mean, the rsync "waits" for the > terminal is "ready" to display text (stays blocked)?it seems so. This is the common behaviour in programs. Look, just a find time: real 0m12.732s user 0m0.220s sys 0m0.804s And find to /dev/null: real 0m6.268s user 0m0.096s sys 0m0.356s (of course, before first find I ran a find to keep information in cache/buffers, etc.) Try with other programs, I guess that you will have same results.> I want the opinion of the developers to know if the "rsync" can be > the "problem" (it was waiting). Or i can continue my investigation on > kernel (driver) and gnome-terminal?try with other programs too, I guess that you will have same "problem". -- Carles Pina i Estany GPG id: 0x8CBDAE64 http://pinux.info Manresa - Barcelona
On 11/30/06, diversos <diversos@posix.brte.com.br> wrote:> The performance was terrible. After some tests with raid0, raid1, non-SATA discs, and using DTrace, i have realized that the problem was the "gnome-terminal". Basically the "-v" switch.I've noticed something similar on my Linux machine. If I run "rsync -v" at a virtual terminal (not through X) to back up my hard disk to a locally attached external disk, rsync runs considerably faster when I select a virtual terminal other than the one to which it is printing its messages. I don't know what is going on here but I agree with Carles that it probably isn't specific to rsync. Matt