Re: [PATCH 1/2] [mmotm] Add notifiers for various swap events

Andi Kleen
2009-12-28T19:23:29Z

>>>> The first question to ask is if compressed swap is worth
>>>> it. Do you have benchmark numbers showing it to be an improvement?
>>>> Are there cases where it is slower than uncompressed swap?
>>>>
>>> http://code.google.com/p/compcache/wiki/Performance
>>
>> That should be included in the changelog of the patches.
>
> Which patches? The driver is already in staging and there's a pointer to
> the home page in

How can it be in staging if there are no hooks for it yet?

>>> ramzswap is an optional module.
>>
>> I have some doubts on the wisdom of making swap algorithms modular.
>> Better compile them in. Then you don't need messy notifiers either.
>
> What's so messy about them? The whole point of having the notifiers is to
> avoid CONFIG_RAMZSWAP in core kernel code...

They make the code much harder to read and follow. When you try to follow
the code flow and you find a notifier it's always a complicated operation
to figure out what code will end up being called.

Sometimes they are needed, but they have a high cost in maintainability.

-Andi
--
ak@linux.intel.com -- Speaking for myself only.