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Bug #235

closed

lttng_enable_channel with too little subbuffers size returns an error that isn't explicit

Added by Raphaël Beamonte over 12 years ago. Updated about 12 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
-
Target version:
LTTng - 2.1 stable
Start date:
05/08/2012
Due date:
% Done:

0%

Estimated time:

Description

When I try to create an UST channel with X subbuffers of size 1024 (or 2048), I just got an error "Enable UST channel failed".

I guess the error is that the subbuffers size is too low (it disappears with 4096), but would it be possible to have a more explicit error ?

Related issues 2 (0 open — 2 closed)

Related to LTTng-tools - Bug #228: Subbuffer sizes and powers of 2Resolved04/26/2012

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Related to LTTng-UST - Bug #339: Subbuffer size of < 4096 are accepted but unable to use the channel afterwardsResolvedMathieu Desnoyers09/17/2012

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 #1

Updated by David Goulet over 12 years ago

This should not happen anymore on lttng-tools 2.1-rcX + .

However, there is a new bug where the lttng-ust tracer fails to create an event if the channel subbuf size is lower than 4096.

See related bugs #339

Please confirm me that this problem is not happening anymore on your side. I'll close it afterwards.

Thanks

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 #2

Updated by David Goulet about 12 years ago

  • Status changed from New to Resolved
  • Target version set to 2.1 stable

Enabling a channel with bad attributes will return a LTTNG_ERR_INVALID code.

Conditions are:

  • subbuf_size < DEFAULT_UST_CHANNEL_SUBBUF_SIZE
  • subbuf_size 0 or (subbuf_size & subbuf_size - 1) 1
  • num_subbuf 0 or (num_subbuf & num_subbuf - 1) 1

The check for power of two is done in the lttng UI. The library does not change the values but rather tell you that if invalid.

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