Re: [PATCH 11/20] blkio: Some CFQ debugging Aid

From: Jeff Moyer
Date: Wed Nov 04 2009 - 13:54:01 EST


Vivek Goyal <vgoyal@xxxxxxxxxx> writes:

> o Some CFQ debugging Aid.

Some CFQ debugging aids. Sorry, I couldn't help myself.

> +config DEBUG_BLK_CGROUP
> + bool
> + depends on BLK_CGROUP
> + default n
> + ---help---
> + Enable some debugging help. Currently it stores the cgroup path
> + in the blk group which can be used by cfq for tracing various
> + group related activity.
> +
> endif # BLOCK
>

> +config DEBUG_CFQ_IOSCHED
> + bool "Debug CFQ Scheduling"
> + depends on CFQ_GROUP_IOSCHED
> + select DEBUG_BLK_CGROUP

This seems wrong. DEBUG_CFQ_IOSCHED sounds like it enables debugging of
CFQ. In your implementation, though, it only enables this in tandem
with the blkio cgroup infrastructure. Please decouple these things.

> +#ifdef CONFIG_DEBUG_BLK_CGROUP
> + /* Store cgroup path */
> + char path[128];
> +#endif

Where does 128 come from? What's wrong with PATH_MAX?

Cheers,
Jeff
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