lkml.org 
[lkml]   [2017]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[RFC PATCH 0/4] Fast noirq bulk page allocator
Date
This series is motivated by a conversation led by Jesper Dangaard Brouer at
the last LSF/MM proposing a generic page pool for DMA-coherent pages. Part of
his motivation was due to the overhead of allocating multiple order-0 that
led some drivers to use high-order allocations and splitting them which
can be very slow if high-order pages are unavailable. This long-overdue
series aims to show that raw bulk page allocation can be achieved relatively
easily without introducing a completely new allocator. A new generic page
pool allocator would then ideally focus on just the DMA-coherent part.

The first two patches in the series restructure the allocator such that
it's relatively easy to build a bulk page allocator. The third patch
alters the per-cpu alloctor to make it exclusive to !irq requests. This
cuts allocation/free overhead by roughly 30% but it may not be noticable
to anyone other than users of high-speed networks (I'm not one). The
fourth patch introduces a bulk page allocator with no in-kernel users as
an example for Jesper and others who want to build a page allocator for
DMA-coherent pages. It hopefully is relatively easy to modify this API
and the one core function to get the semantics they require. Note that
Patch 3 is not required for patch 4 but it may be desirable if the bulk
allocations happen from !IRQ context.

include/linux/gfp.h | 23 ++++
mm/page_alloc.c | 329 ++++++++++++++++++++++++++++++++++++----------------
2 files changed, 254 insertions(+), 98 deletions(-)

--
2.11.0

\
 
 \ /
  Last update: 2017-01-04 12:12    [W:0.089 / U:0.508 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site