Re: [PATCHv6 1/8] zsmalloc: add to mm/

From: Seth Jennings
Date: Fri Feb 22 2013 - 12:58:19 EST

On 02/22/2013 03:40 AM, Joonsoo Kim wrote:
> On Wed, Feb 20, 2013 at 04:04:41PM -0600, Seth Jennings wrote:
>> =========
>> This patch introduces zsmalloc as new code, however, it already
>> exists in drivers/staging. In order to build successfully, you
>> must select EITHER to driver/staging version OR this version.
>> Once zsmalloc is reviewed in this format (and hopefully accepted),
>> I will create a new patchset that properly promotes zsmalloc from
>> staging.
>> =========
>> This patchset introduces a new slab-based memory allocator,
>> zsmalloc, for storing compressed pages. It is designed for
>> low fragmentation and high allocation success rate on
>> large object, but <= PAGE_SIZE allocations.
>> zsmalloc differs from the kernel slab allocator in two primary
>> ways to achieve these design goals.
>> zsmalloc never requires high order page allocations to back
>> slabs, or "size classes" in zsmalloc terms. Instead it allows
>> multiple single-order pages to be stitched together into a
>> "zspage" which backs the slab. This allows for higher allocation
>> success rate under memory pressure.
> I have one more concern. It may be possibly stale question.
> I think that zsmalloc makes system memories more fragmented.
> Pages for zsmalloc can't be moved and may be spread at random location
> because it's order is just 0, so high order allocation success rate
> will be decreased. How do you think about it?

For now, this is true. NUMA and migration awareness, IMO, are the
highest priorities for additional development on zsmalloc (after merging).


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