linux-kernel - Re: [PATCH] mm/vmalloc: Keep a separate lazy-free list

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Message-ID: <CACZ9PQXze0dPHz9vf8o+Cpzv8j__Oe+HBJmv8H=bCNie_x+CyA@mail.gmail.com>
Date:	Sat, 23 Apr 2016 13:21:08 +0200
From:	Roman Peniaev <r.peniaev@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Chris Wilson <chris@...is-wilson.co.uk>,
	intel-gfx@...ts.freedesktop.org,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Toshi Kani <toshi.kani@...com>,
	Shawn Lin <shawn.lin@...k-chips.com>, linux-mm@...ck.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/vmalloc: Keep a separate lazy-free list

On Fri, Apr 22, 2016 at 11:49 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Fri, 15 Apr 2016 12:14:31 +0100 Chris Wilson <chris@...is-wilson.co.uk> wrote:
>
>> > > purge_fragmented_blocks() manages per-cpu lists, so that looks safe
>> > > under its own rcu_read_lock.
>> > >
>> > > Yes, it looks feasible to remove the purge_lock if we can relax sync.
>> >
>> > what is still left is waiting on vmap_area_lock for !sync mode.
>> > but probably is not that bad.
>>
>> Ok, that's bit beyond my comfort zone with a patch to change the free
>> list handling. I'll chicken out for the time being, atm I am more
>> concerned that i915.ko may call set_page_wb() frequently on individual
>> pages.
>
> Nick Piggin's vmap rewrite.  20x (or more) faster.
> https://lwn.net/Articles/285341/
>
> 10 years ago, never finished.

But that's exactly what we are changing making 20.5x faster :)

--
Roman