Re: [dm-devel] new dm-bufio

[Mikulas Patocka <mpatocka redhat com>]

On Tue, 23 Aug 2011, Joe Thornber wrote:

> On Mon, Aug 22, 2011 at 04:05:28PM -0400, Mikulas Patocka wrote:
> > I uploaded new dm-bufio patch at 
> > http://people.redhat.com/mpatocka/patches/kernel/dm-thinp-bufio/dm-bufio.patch
> > 
> > It reports the number of allocated bytes in 
> > "/sys/module/dm_bufio/parameters/". There is a file "total_allocated" that 
> > contains the number of bytes allocated for buffer cache. There are files 
> > "allocated_get_free_pages", "allocated_kmalloc", "allocated_vmalloc" that 
> > contain a number of allocated bytes with each method.
> > 
> > BTW. if you store "1" in "cache_size", it switches to a mode where it 
> > won't allocate any memory during operation, relying only on preallocated 
> > reserves --- useful for testing reservation deadlocks.
> 
> Great stuff, will merge straight away.
> 
> Are these stats broken down by bufio client?  ie. can we tell which 
> pool/thinps are consuming all the space?

No, it would me much more complicated to export such numbers.

> Would it be possible to record a high watermark as well?  This would
> be very useful for benchmarking.  eg, we'd run a heavy load, then be
> able to get the peak memory usage.  (Resetting this hwm would also be useful).

I uploaded new version to
http://people.redhat.com/mpatocka/patches/kernel/dm-thinp-bufio/dm-bufio.patch

There is file "/sys/module/dm_bufio/parameters/peak_allocated" which 
contains peak memory consumption. You can reset the value by writing 0 to 
the file.

Mikulas


> - Joe
>