423036 - Decommit for huge_[mp]alloc() and base_alloc(), fix huge_palloc()

Status: RESOLVED FIXED

(Core :: XPCOM, enhancement)

Description

[Jason Evans]

Attachment: huge_[mp]alloc()/base_alloc() decommit, huge_palloc() fix

The attached patch adds code that decommits unused pages for two types of allocations: base and huge.  Base allocations are for internal use by jemalloc, and in the common case, there are ~1020KiB of mapped base pages that are unused.  Huge allocations appear to be infrequent in Firefox, but they do happen, and since they are rounded up to the nearest multiple of 1MiB, it is common for there to be many trailing unused pages.

This patch also fixes huge_palloc() (handles large alignment cases for posix_memalign()) to work on Windows.  I have been unable to come up with a usage scenario that even causes that function to be called.  posix_memalign() was only recently added, so there are very few callers right now, but it should be fixed at some point.

Comment 1

[Jason Evans]

Attachment: huge_[mp]alloc()/base_alloc() decommit, huge_palloc() fix

This patch revision adds a missing '}'.

Comment 2

[Stuart Parmenter]

Comment on attachment 309585 [details] [diff] [review]
huge_[mp]alloc()/base_alloc() decommit, huge_palloc() fix

this will save us potentially a lot of memory in certain cases.  we should get this in

Comment 3

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Comment on attachment 309585 [details] [diff] [review]
huge_[mp]alloc()/base_alloc() decommit, huge_palloc() fix

a=me for 1.9

Comment 4

[Stuart Parmenter]

checked in