Philipp Stephani <p.stepha...@gmail.com> writes:
Hi Philipp,
> t and "-o ControlMaster=auto -o ControlPath='tramp.%%C' -o
> ControlPersist=no" (i.e. the defaults).
>
>> Could you set `tramp-verbose' to 6 and verify, whether these options are
>> used? You could send the traces to me for analyzing, if you prefer.
>
> They seem to be used, the output is:
>
> Tramp: Opening connection for HOSTNAME using ssh...
> Tramp: Sending command ‘exec ssh -q -o ControlMaster=auto -o
> ControlPath='tramp.%C' -o ControlPersist=no -e none HOSTNAME’
> Tramp: Waiting for prompts from remote shell...done
> Tramp: Found remote shell prompt on ‘HOSTNAME’
> Tramp: Opening connection for HOSTNAME using ssh...done
Yes. So we don't need to care about ControlMaster; Tramp does everything
what's possible here.
> The form I've evaluated is just
> (let ((default-directory "/ssh:HOSTNAME:/"))
> (start-file-process "" nil "true"))
>
> This takes 2 seconds per invocation on my machine:
> (benchmark-run 10
> (let ((default-directory "/ssh:HOSTNAME:/"))
> (start-file-process "" nil "true")))
> (21.287248981 78 6.104474747000001)
There is a difference wrt verbosity level. See:
(benchmark-run 10
(let ((tramp-verbose 10)
(default-directory "/ssh::/"))
(start-file-process "" nil "true")))
(8.524027585 16 3.5059282540000005)
(benchmark-run 10
(let ((tramp-verbose 3)
(default-directory "/ssh::/"))
(start-file-process "" nil "true")))
(6.871181527 9 2.210354418999998)
(benchmark-run 10
(let ((tramp-verbose 0)
(default-directory "/ssh::/"))
(start-file-process "" nil "true")))
(3.986375167 6 1.6585357770000044)
This is with Tramp 2.5.0-pre from git master. All these numbers are
taken after I had open /ssh::/ already in another buffer. For better
comparision, you might set tramp-verbose to 0.
> If you're interested, I've profiled Tramp with ELP (on Emacs master),
> here's the report:
Thanks. What was the code you have profiled with? Just the same as for
the benchmark? 48 sec sounds very long compared to the benchmark results.
> tramp-file-name-handler 79
> 48.196645538 0.6100841207
> tramp-sh-file-name-handler 59
> 47.933230473 0.8124276351
> tramp-handle-start-file-process 11
> 23.966547321 2.1787770292
> tramp-sh-handle-make-process 11
> 23.916336605 2.1742124187
> tramp-maybe-open-connection 77
> 23.538912846 0.3057001668
> tramp-process-actions 11
> 16.095361023 1.4632146384
Well, tramp-process-actions runs the handshaking (checking for passwords
and other things to set up). Maybe we shall investigate in more detail
where the time is spent.
> tramp-check-for-regexp 27300
> 13.363068022 0.0004894896
> tramp-search-regexp 27520
> 8.4726394889 0.0003078720
tramp-check-for-regexp takes only negligible time per call. But applying
it 27300 times sounds too much to me. tramp-search-regexp is mainly
called in tramp-check-for-regexp.
> tramp-send-command 198
> 7.0239918969 0.0354747065
> tramp-wait-for-output 176
> 6.898226061 0.0391944662
> tramp-accept-process-output 2955
> 6.8919202430 0.0023322911
> tramp-wait-for-regexp 187
> 6.8587603229 0.0366778626
> tramp-open-connection-setup-interactive-shell 11
> 6.817871086 0.6198064623
Well, tramp-open-connection-setup-interactive-shell is needed for
interactive shells. But in start-file-process, some of its actions might
be skipped I believe.
> tramp-get-connection-property 56391
> 2.8474465550 5.049...e-05
> tramp-send-command-and-check 44
> 1.8092037689 0.0411182674
> tramp-barf-unless-okay 33
> 1.345802245 0.0407818862
> tramp-send-command-and-read 33
> 1.3418833959 0.0406631332
> tramp-debug-message 785
> 1.1342730509 0.0014449338
> tramp-open-shell 11
> 1.106302197 0.1005729269
> tramp-get-hash-table 56732
> 0.7261888440 1.280...e-05
> [...]
These calls do not take too much time per call. However,
tramp-get-connection-property is called 56391 times. Maybe i change it
to be a defsubst?
> I'm not sure what the culprit is, but my method (that doesn't use
> Tramp's connections) is reliably 500 times faster.
500 times faster is remarkable. But Tramp needs some overhead for setup
and writing traces. Anyway, I'll play with it; maybe I could speed it up
somehow.
Best regards, Michael.
