[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Should use of mallopt depend on DOUG_LEA_MALLOC?

From: Stefan Monnier
Subject: Re: Should use of mallopt depend on DOUG_LEA_MALLOC?
Date: Fri, 13 Dec 2019 10:22:51 -0500
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)

>> I also don't really have any idea what the mallopt calls do (that is, I
>> can see in the documentation that they modify such and such parameter of
>> the allocator, but I don't know what that means in practice: faster,
>> slower, less RAM, more RAM, etc).

For those in `init_alloc_once_for_pdumper`, I can't help you.
But the ones conditionalized on `mmap_lisp_allowed_p` are used not as
optimizations but to prevent use of mmap within the malloc
implementation in the two known cases where it can break our
(unportable) assumptions:

- when we use MSB bits for the Lisp_Object tags and hence cannot use all
  of the addressable memory for Lisp objects.
  [ Hopefully, there are no platforms in this category remaining, but
  I don't know this to be the case for sure.  ]

- when we're about to do the unexec dump because the unexec code doesn't
  handle those mmap'd areas.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]