Re: [PATCH 2/2] mm: add a field to store names for private anonymous memory

[Pekka Enberg <penberg@kernel.org>]

On 07/12/2013 11:55 AM, Peter Zijlstra wrote:
> Mmap the file PROT_READ|PROT_WRITE|PROT_EXEC, map the _entire_ file, not just
> the text section; make the symbol table larger than you expect. Then write the
> symbol name after you've jit'ed the text but before you use it.
>
> IIRC you once told me you never overwrite text but always append new symbols.
> So you can basically fill the DSO with text/symbols use mmap memory writes.

I don't but I think Hotspot, for example, does recompile method. Dunno
if it's a problem really, we could easily come up with a versioning
scheme for the methods and teach perf to treat the different memory
regions as the same method.

On 07/12/2013 11:55 AM, Peter Zijlstra wrote:
> Once the DSO is full -- equal to your previous anon-exec region being full,
> you simply mmap a new DSO.
>
> Wouldn't that work?

Okay and then whenever 'perf top' sees a non-mapped IP it reloads the
DSO (if it has changed)?

Yeah, I could see that working. It doesn't solve the problems Ingo 
mentioned which are also important, though.

			Pekka

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