On Fri, 2006-01-20 at 16:50 -0800, Andrew Morton wrote:
> For linux-scsi reference, Chase's /proc/slabinfo says:
>
> scsi_cmd_cache 1547440 1547440 384 10 1 : tunables 54 27 8 :
> slabdata 154744 154744 0
There's another curiosity about this: the linux command stack is pretty
well counted per scsi device (it's how we control queue depth), so if a
driver leaks commands we see it not by this type of behaviour, but by
the system hanging (waiting for all the commands the mid-layer thinks
are outstanding to return). So, the only way we could leak commands
like this is in the mid-layer command return logic ... and I can't find
anywhere this might happen.
The sequence is:
driver -> cmd->scsi_done() -> blk softirq -> scsi_softirq_done() ->
scsi_finish_cmd() (where the queue counts are decremented, so anything
after here could leak commands if the rest of the chain is broken) ->
cmd->done() (which is the ULD completion callback) ->
scsi_io_completion() (frees the sg table, so if the sgpool slabs aren't
out of whack we must be past here) -> scsi_end_request() ->
scsi_next_command() -> scsi_put_command() (which is where the command
goes back to the slab).
James
> > Curious - the -s... were you expecting the ring buffer
> > to exceed 16384?
>
> It can sometimes be quite large. I always say -s 1000000 to make sure
> everything got there.
>
> > I don't think my (boot time) buffer does.
>
> It's compile-time configurable with CONFIG_LOG_BUF_SHIFT and boot-time
> configurable with log_buf_len=n.
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