From 93e6c8a01b8c4a499b66eeeba2558cca2260de5f Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 21 Feb 2012 20:07:29 -0500 Subject: [PATCH] Document that num-subbuf and subbuf-size need to be power of 2 Reported-by: Tan Dung Le Tran Acked-by: David Goulet Signed-off-by: Mathieu Desnoyers --- doc/man/lttng.1 | 2 ++ src/bin/lttng/commands/enable_channels.c | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/doc/man/lttng.1 b/doc/man/lttng.1 index 8416f4c21..2445b05ac 100644 --- a/doc/man/lttng.1 +++ b/doc/man/lttng.1 @@ -274,8 +274,10 @@ file. Subbuffer size in bytes (default: 4096, kernel default: 262144) \-\-num-subbuf Number of subbufers (default: 8, kernel default: 4) + Needs to be a power of 2 for kernel and ust tracers \-\-switch-timer Switch subbuffer timer interval in usec (default: 0) + Needs to be a power of 2 for kernel and ust tracers \-\-read-timer Read timer interval in usec (default: 200) .fi diff --git a/src/bin/lttng/commands/enable_channels.c b/src/bin/lttng/commands/enable_channels.c index 91345e051..4e56b3ca5 100644 --- a/src/bin/lttng/commands/enable_channels.c +++ b/src/bin/lttng/commands/enable_channels.c @@ -104,10 +104,14 @@ static void usage(FILE *ofp) fprintf(ofp, " (default: %u, kernel default: %u)\n", DEFAULT_CHANNEL_SUBBUF_SIZE, DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE); + fprintf(ofp, " Needs to be a power of 2 for\n"); + fprintf(ofp, " kernel and ust tracers\n"); fprintf(ofp, " --num-subbuf NUM Number of subbufers\n"); fprintf(ofp, " (default: %u, kernel default: %u)\n", DEFAULT_CHANNEL_SUBBUF_NUM, DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM); + fprintf(ofp, " Needs to be a power of 2 for\n"); + fprintf(ofp, " kernel and ust tracers\n"); fprintf(ofp, " --switch-timer USEC Switch timer interval in usec (default: %u)\n", DEFAULT_CHANNEL_SWITCH_TIMER); fprintf(ofp, " --read-timer USEC Read timer interval in usec (default: %u)\n", -- 2.34.1