From: Jérémie Galarneau Date: Tue, 5 May 2020 22:54:32 +0000 (-0400) Subject: sessiond: enforce mmap output type for kernel metadata channel X-Git-Tag: v2.13.0-rc1~634 X-Git-Url: https://git.lttng.org/?a=commitdiff_plain;h=d42266a417afa6e8ca6024590b8282002aebca07;hp=d42266a417afa6e8ca6024590b8282002aebca07;p=lttng-tools.git sessiond: enforce mmap output type for kernel metadata channel A follow-up fix causes the consumer daemon to accumulate metadata packets into a complete "unit" that can be parsed before sending it to the relay daemon. The consumer daemon will also need to extract the contents of the metadata cache when computing a rotation position (follow-up fix too). Hence, it is not possible to rely on the splice back-end as the consumer daemon may need to accumulate more content than can be backed by the ring buffer's underlying pages. In both cases, the splice output mode could still be used when combined with a memfd, but I see no tangible benefit. Moreover, it would require a 3.17 kernel. Curiously the kernel metadata channel configuration appears to be hard-coded twice; once in the ltt_kernel_session's ltt_kernel_metadata, and once again in kernel_consumer_add_metadata(). kernel_consumer_add_metadata is modified to use the kernel session's metadata configuration. Signed-off-by: Jérémie Galarneau Change-Id: Ia4cad82f595d3eee50d081851c234d4c2ef7ee5f ---