Difference between revisions of "Ureadahead"

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[[Category:Boot process (English)]]
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[[Category:Boot process]]
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{{Note|ureadahead package is orphaned because Systemd comes with its own readahead implementation. See [[Improve Boot Performance#Readahead]].}}
 
Ureadahead (Über-readahead) is used to speed up the boot process. It works by reading all the files required during boot and makes pack files for quicker access, then during boot reads these files in advance, thus minimizes the access times for the harddrives. It's intended to replace sreadahead.
 
Ureadahead (Über-readahead) is used to speed up the boot process. It works by reading all the files required during boot and makes pack files for quicker access, then during boot reads these files in advance, thus minimizes the access times for the harddrives. It's intended to replace sreadahead.
  
 
== Requirements ==
 
== Requirements ==
Currently, ureadahead needs a kernel patch to work. This is provided by ying in the [http://aur.archlinux.org/packages.php?ID=37895 AUR].
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Currently, ureadahead needs a kernel patch to work. You can use {{AUR|linux-ureadahead}}.
  
Ureadahead is also [http://aur.archlinux.org/packages.php?ID=37889 available], of course.
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The user-space package is called {{AUR|ureadahead}}.
  
 
== How it works ==
 
== How it works ==
Line 15: Line 16:
  
 
== Using ureadahead ==
 
== Using ureadahead ==
First you need the patched kernel. After the installation you need to make ureadahead start on boot. Simply create the file /etc/rc.d/functions.d/ureadahead and add
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First you need the patched kernel. After the installation you need to make ureadahead start on boot. Simply create the file {{ic|/etc/rc.d/functions.d/ureadahead}} and add:
 
  ureadahead() {
 
  ureadahead() {
 
  /sbin/ureadahead --timeout=240 &
 
  /sbin/ureadahead --timeout=240 &
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  add_hook sysinit_end ureadahead
 
  add_hook sysinit_end ureadahead
 
to start it after sysinit.  
 
to start it after sysinit.  
{{Note|You can also use sysinit_premount to start it before it mounts all the other filesystems in /etc/fstab, but this might create issues depending on your system (e.g. if you have /var on a separate partition).}}
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{{Note|You can also use {{ic|sysinit_premount}} to start it before it mounts all the other filesystems in {{ic|/etc/fstab}}, but this might create issues depending on your system (e.g. if you have {{ic|/var}} on a separate partition).}}
  
 
Now you should be good to go.
 
Now you should be good to go.
  
 
== Configuration ==
 
== Configuration ==
There isn't really much in the way of configuring ureadahead. You can specify which mountpoint to trace with
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There are few configuration options for ureadahead. You can specify which mountpoint to trace with:
$ ureadahead /<mountpoint>
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{{bc|$ ureadahead /<mountpoint>}}
 
though it should automatically trace all needed mountpoints during boot.
 
though it should automatically trace all needed mountpoints during boot.
  
You can also run it with --force-trace to force a retrace, however it's better just to remove the pack files and reboot.
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You can also run it with {{Ic|--force-trace}} to force a retrace, however it is better to remove the pack files and reboot.
  
The pack files are in /var/lib/ureadahead and are named after their mountpoint (i.e. pack for root, home.pack for /home).
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The pack files are in {{ic|/var/lib/ureadahead}} and are named after their mountpoint (i.e. {{ic|pack}} for root, {{ic|home.pack}} for {{ic|/home}}).
  
 
== Questions ==
 
== Questions ==
 
{{FAQ
 
{{FAQ
 
|question=Why does this take so long time tracing?
 
|question=Why does this take so long time tracing?
|answer=If you didn't supply --timeout, you need to kill it manually. Either just ^C it, or use pkill ureadahead.}}
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|answer=If you didn't supply --timeout, you need to kill it manually. Either just {{Keypress|^C}} it, or use {{ic|pkill ureadahead}}.}}
  
 
== Helping out ==
 
== Helping out ==
 
If your boot actually becomes slower after generating the pack files and you're sure ureadahead is to blame, then file a bug report. To get useful data, make sure both ureadahead and bootchart installed.
 
If your boot actually becomes slower after generating the pack files and you're sure ureadahead is to blame, then file a bug report. To get useful data, make sure both ureadahead and bootchart installed.
  
First, disable ureadahead on boot (remove /etc/rc.d/functions.d/ureadahead) and remove the pack files in /var/lib/ureadahead, then reboot and save the bootchart.
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First, disable ureadahead on boot (remove {{ic|/etc/rc.d/functions.d/ureadahead}}) and remove the pack files in {{ic|/var/lib/ureadahead}}, then reboot and save the bootchart.
  
Then, reenable ureadahead (recreate the file in /etc/rc.d/functions.d/ureadahead) and reboot. Save this bootchart too.
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Then, reenable ureadahead (recreate the file in {{ic|/etc/rc.d/functions.d/ureadahead}}) and reboot. Save this bootchart too.
  
 
Finally, reboot once more, and save the final bootchart.
 
Finally, reboot once more, and save the final bootchart.
  
Now you should have 3 bootcharts, one without ureadahead, one when ureadahead is tracing and one when it's running normally. Then, as root, run
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Now you should have 3 bootcharts, one without ureadahead, one when ureadahead is tracing and one when it's running normally. Then, as root, run:
$ ureadahead --dump > ureadahead.dump
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{{bc|# ureadahead --dump > ureadahead.dump}}
 
to dump the contents of the pack file. Create a bug report on the ureadahead launchpad file and attach the bootcharts along with the dump.
 
to dump the contents of the pack file. Create a bug report on the ureadahead launchpad file and attach the bootcharts along with the dump.
{{Note|I don't know how welcome this will be to the ubuntu developers, since we're using arch. If you still want to help, give it a try and see if they're interested.}}
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{{Note|I do not know how welcome this will be to the ubuntu developers, since we're using arch. If you still want to help, give it a try and see if they're interested.}}
  
 
== More resources ==
 
== More resources ==
 
*[https://launchpad.net/ubuntu/+source/ureadahead ureadahead homepage]
 
*[https://launchpad.net/ubuntu/+source/ureadahead ureadahead homepage]
*[http://aur.archlinux.org/packages.php?ID=37889 ureadahead package on AUR]
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*[https://aur.archlinux.org/packages.php?ID=37889 ureadahead package on AUR]
*[http://aur.archlinux.org/packages.php?ID=37948 Nvidia driver for the patched kernel]
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*[https://aur.archlinux.org/packages.php?ID=37948 Nvidia driver for the patched kernel]
*[http://aur.archlinux.org/packages/kernel26-yi/kernel26-yi/0001-trace-add-trace-events-for-open-exec-an.patch kernel patch for compiling your own kernel]{{Linkrot|2011|09|05}}
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Revision as of 05:00, 21 June 2013

Note: ureadahead package is orphaned because Systemd comes with its own readahead implementation. See Improve Boot Performance#Readahead.

Ureadahead (Über-readahead) is used to speed up the boot process. It works by reading all the files required during boot and makes pack files for quicker access, then during boot reads these files in advance, thus minimizes the access times for the harddrives. It's intended to replace sreadahead.

Requirements

Currently, ureadahead needs a kernel patch to work. You can use linux-ureadaheadAUR.

The user-space package is called ureadaheadAUR.

How it works

When run without any arguments, ureadahead checks for pack files in /var/lib/ureadahead, and if none are found or if the packfiles are older than a month, it starts tracing the boot process. When tracing, it waits for either a TERM or INT signal before generating the pack file.

Otherwise, if the file is up to date, it just reads the pack file in preparation for the boot.

It works for both SSDs and traditional harddrives and automatically optimizes the pack files depending on which you have.

Using ureadahead

First you need the patched kernel. After the installation you need to make ureadahead start on boot. Simply create the file /etc/rc.d/functions.d/ureadahead and add:

ureadahead() {
/sbin/ureadahead --timeout=240 &
}

add_hook sysinit_end ureadahead

to start it after sysinit.

Note: You can also use sysinit_premount to start it before it mounts all the other filesystems in /etc/fstab, but this might create issues depending on your system (e.g. if you have /var on a separate partition).

Now you should be good to go.

Configuration

There are few configuration options for ureadahead. You can specify which mountpoint to trace with:

$ ureadahead /<mountpoint>

though it should automatically trace all needed mountpoints during boot.

You can also run it with --force-trace to force a retrace, however it is better to remove the pack files and reboot.

The pack files are in /var/lib/ureadahead and are named after their mountpoint (i.e. pack for root, home.pack for /home).

Questions

Template:FAQ

Helping out

If your boot actually becomes slower after generating the pack files and you're sure ureadahead is to blame, then file a bug report. To get useful data, make sure both ureadahead and bootchart installed.

First, disable ureadahead on boot (remove /etc/rc.d/functions.d/ureadahead) and remove the pack files in /var/lib/ureadahead, then reboot and save the bootchart.

Then, reenable ureadahead (recreate the file in /etc/rc.d/functions.d/ureadahead) and reboot. Save this bootchart too.

Finally, reboot once more, and save the final bootchart.

Now you should have 3 bootcharts, one without ureadahead, one when ureadahead is tracing and one when it's running normally. Then, as root, run:

# ureadahead --dump > ureadahead.dump

to dump the contents of the pack file. Create a bug report on the ureadahead launchpad file and attach the bootcharts along with the dump.

Note: I do not know how welcome this will be to the ubuntu developers, since we're using arch. If you still want to help, give it a try and see if they're interested.

More resources