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

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Message-Id: <20160422144957.64619ee9b19991e4fdf89668@linux-foundation.org>
Date:	Fri, 22 Apr 2016 14:49:57 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Chris Wilson <chris@...is-wilson.co.uk>
Cc:	Roman Peniaev <r.peniaev@...il.com>,
	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, 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.