Re: 2.6.11-rc1-mm1

[Karim Yaghmour <karim@opersys.com>]

Andi Kleen wrote:
> When you have a timing bug and your logger starts to block randomly
> you also won't debug anything. Fix is to make your buffers bigger.

relayfs allows you to choose which is best for you.

>From Documentation/filesystems/relayfs.txt:
...
int    relay_open(channel_path, bufsize, nbufs, channel_flags,
		  channel_callbacks, start_reserve, end_reserve,
		  rchan_start_reserve, resize_min, resize_max, mode,
		  init_buf, init_buf_size)
...
- resize_min - if set, this signifies that the channel is
  auto-resizeable.  The value specifies the size that the channel will
  try to maintain as a normal working size, and that it won't go
  below.  The client makes use of the resizing callbacks and
  relay_realloc_buffer() and relay_replace_buffer() to actually effect
  the resize.

- resize_max - if set, this signifies that the channel is
  auto-resizeable.  The value specifies the maximum size the channel
  can have as a result of resizing.
...

LTT uses fixed-sized channels, but the implementation of printk-
over-relayfs used resize_min and resize_max to allow automatic
sizing (grep for relay_open):
http://www.opersys.com/ftp/pub/relayfs/patch-printk-on-relayfs-2.6.0-test1

... now I'm going to get some sleep ... I'll catch up later with
further discussion ...

Karim
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