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

Started byAndrew Morton <akpm@linux-foundation.org>
First post2016-04-23 00:00 +0200
Last post2016-04-23 13:30 +0200
Articles 2 — 2 participants

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  Re: [PATCH] mm/vmalloc: Keep a separate lazy-free list Andrew Morton <akpm@linux-foundation.org> - 2016-04-23 00:00 +0200
    Re: [PATCH] mm/vmalloc: Keep a separate lazy-free list Roman Peniaev <r.peniaev@gmail.com> - 2016-04-23 13:30 +0200

#1385487 — Re: [PATCH] mm/vmalloc: Keep a separate lazy-free list

FromAndrew Morton <akpm@linux-foundation.org>
Date2016-04-23 00:00 +0200
SubjectRe: [PATCH] mm/vmalloc: Keep a separate lazy-free list
Message-ID<rqRhh-pl-49@gated-at.bofh.it>
On Fri, 15 Apr 2016 12:14:31 +0100 Chris Wilson <chris@chris-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.

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#1385637

FromRoman Peniaev <r.peniaev@gmail.com>
Date2016-04-23 13:30 +0200
Message-ID<rr3V8-2ca-7@gated-at.bofh.it>
In reply to#1385487
On Fri, Apr 22, 2016 at 11:49 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Fri, 15 Apr 2016 12:14:31 +0100 Chris Wilson <chris@chris-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

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