sreadahead tries to access non-existing files

[FriedChicken]

Binary package hint: sreadahead

It seems as sreadahead expects some files to be available but they don't exist.

$ sudo sreadahead --no-fork
tracing/events/fs/do_sys_open/enable: open failed (No such file or directory)
tracing/tracing_enabled: open failed (No such file or directory)
sda/queue/read_ahead_kb: open failed (No such file or directory)
/var/run/xauth/A:0-tdE5Ws: open failed (No such file or directory)

[Scott James Remnant (Canonical) (canonical-scott)]

On Mon, 2009-09-28 at 23:01 +0000, FriedChicken wrote:

> It seems as sreadahead expects some files to be available but they don't
> exist.
>
What kernel version are you using?

Provide "uname -a"

 status incomplete

Scott
--
Scott James Remnant
<email address hidden>

[FriedChicken (domlyons)]

This happens on two systems, both have all recent updates:
   $ uname -a
   Linux amilo 2.6.31-11-generic #38-Ubuntu SMP Fri Oct 2 11:55:55 UTC 2009 i686 GNU/Linux

By the way, the /var/run/xauth/-error has gone:
    $ sudo sreadahead --no-fork
   tracing/events/fs/do_sys_open/enable: open failed (No such file or directory)
   tracing/tracing_enabled: open failed (No such file or directory)
   sda/queue/read_ahead_kb: open failed (No such file or directory

[Matt Zimmerman (mdz)]

it looks like those particular errors are only displayed when sreadahead is doing readahead (as opposed to profiling), so it looks like those paths ended up in the pack somehow.

Assuming you can still reproduce this, can you attach /var/lib/sreadahead/pack to this bug?

[Matt Zimmerman (mdz)]

This sort of error could very well be normal, as files which existed when profiling was done could have been removed later.

[FriedChicken (domlyons)]

Yes, I guess you are right:

   $ cat /var/lib/sreadahead/pack | LANG=C grep tracing/events/fs/do_sys_open/enable
   Binary file (standard input) matches

   $ cat /var/lib/sreadahead/pack | LANG=C grep tracing/tracing_enabled
   Binary file (standard input) matches

   $ cat /var/lib/sreadahead/pack | LANG=C grep sda/queue/read_ahead_kb
   Binary file (standard input) matches

[FriedChicken (domlyons)]

I assume the given path snippets are part of
   - /sys/kernel/debug/tracing/events/fs/do_sys_open
   - /sys/kernel/debug/tracing/tracing_enabled
   - /sys/block/sda/queue/read_ahead_kb

I have neither a clue why this files are in the pack-file nor why the paths are incomplete, but maybe it helps you in some way.

[Scott James Remnant (Canonical) (canonical-scott)]

Err, thanks Matt.

However your diagnosis is quite incorrect, in fact this bug is more interesting. The missing paths that it can't open are the debugfs paths that sreadahead uses for tracing.

[Scott James Remnant (Canonical) (canonical-scott)]

ureadahead doesn't try and read these relative paths (which are caused by the tracing), you'll still see warnings about files that vanished between the trace and the readahead passes of course

[Scott James Remnant (Canonical) (canonical-scott)]

ureadahead has now replaced sreadahead in both karmic (via -updates) and lucid

[Pieter Leclerc (pieterleclerc-deactivatedaccount)]

Here it says that it's the other way around: "sreadahead has been replaced by ureadahead": http://packages.ubuntu.com/lucid/sreadahead