Re: [RFC PATCH 1/1] ext4: Try to better reuse recently freed space

[Dmitry Monakhov <dmonakhov@openvz.org>]

On Tue, 1 Apr 2014 01:30:18 -0400, Theodore Ts'o <tytso@mit.edu> wrote:
> On Mon, Dec 02, 2013 at 05:32:06PM +0100, Lukáš Czerner wrote:
> > Hi all,
> > 
> > this is the patch I send a while ago to fix the issue I've seen with
> > a global allocation goal. This might no longer apply to the current
> > kernel and it might not be the best approach, but I use this example
> > just to start a discussion about those allocation goals and how to
> > use, or change them.
> > 
> > I think that we agree that the long term fix would be to have free
> > extent map. But we might be able to do something quickly, unless
> > someone commits to make the free extent map reality :)
> 
> Hi Andreas,
> 
> We discussed possibly applying this patch last week at the ext4
> workshop, possibly as early as for the 3.15 merge window:
> 
> 	http://patchwork.ozlabs.org/patch/295956/
> 
> However, I'm guessing that Lustre has the workload which is most
> likely to regress if we were to simply apply this patch.  But, it's
> likely it will improve things for many/most other ext4 workloads.
> 
> We did talk about trying to assemble some block allocation performance
> tests so we can better measure proposed changes to the block
> allocator, but that's not something we have yet.  However, this global
BTW where this can I find this discussion? I would like to cooperate
this that activity. Please CC me next time you will disscuss allocation
performance mesurments. At Parallels we run https://oss.oracle.com/~mason/compilebench/
as load simulator.
> goal is definitely causing problems for a number of use cases,
> including thinp and being flash friendly.
> 
> Would you be willing to apply this patch and then run some benchmarks
> to see if Lustre would be impacted negatively if we were to apply this
> patch for the next development cycle (i.e., not for 3.15, but for the
> next merge window)?
> 
> Thanks,
> 
> 							- Ted
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