From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Joonsoo Kim <js1304@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE
Date: Thu, 18 Feb 2016 18:55:36 +0900 [thread overview]
Message-ID: <20160218095536.GA503@swordfish> (raw)
In-Reply-To: <CAAmzW4O-yQ5GBTE-6WvCL-hZeqyW=k3Fzn4_9G2qkMmp=ceuJg@mail.gmail.com>
Hello Joonsoo,
On (02/18/16 17:28), Joonsoo Kim wrote:
> 2016-02-18 12:02 GMT+09:00 Sergey Senozhatsky
> <sergey.senozhatsky.work@gmail.com>:
> > ZS_MAX_PAGES_PER_ZSPAGE does not have to be order or 2. The existing
> > limit of 4 pages per zspage sets a tight limit on ->huge classes, which
> > results in increased memory wastage and consumption.
>
> There is a reason that it is order of 2. Increasing ZS_MAX_PAGES_PER_ZSPAGE
> is related to ZS_MIN_ALLOC_SIZE. If we don't have enough OBJ_INDEX_BITS,
> ZS_MIN_ALLOC_SIZE would be increase and it causes regression on some
> system.
Thanks!
do you mean PHYSMEM_BITS != BITS_PER_LONG systems? PAE/LPAE? isn't it
the case that on those systems ZS_MIN_ALLOC_SIZE already bigger than 32?
MAX_PHYSMEM_BITS 36
_PFN_BITS 36 - 12
OBJ_INDEX_BITS (32 - (36 - 12) - 1)
ZS_MIN_ALLOC_SIZE MAX(32, 4 << 12 >> (32 - (36 - 12) - 1)) != 32
-ss
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next prev parent reply other threads:[~2016-02-18 9:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 3:02 [RFC PATCH 0/3] mm/zsmalloc: increase density and reduce memory wastage Sergey Senozhatsky
2016-02-18 3:02 ` [RFC PATCH 1/3] mm/zsmalloc: introduce zs_get_huge_class_size_watermark() Sergey Senozhatsky
2016-02-18 3:02 ` [RFC PATCH 2/3] zram: use zs_get_huge_class_size_watermark() Sergey Senozhatsky
2016-02-18 3:02 ` [RFC PATCH 3/3] mm/zsmalloc: change ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky
2016-02-18 4:41 ` Sergey Senozhatsky
2016-02-18 4:46 ` Sergey Senozhatsky
2016-02-18 5:03 ` Sergey Senozhatsky
2016-02-18 8:28 ` Joonsoo Kim
2016-02-18 9:55 ` Sergey Senozhatsky [this message]
2016-02-18 10:19 ` Sergey Senozhatsky
2016-02-19 1:19 ` Joonsoo Kim
2016-02-19 4:16 ` Sergey Senozhatsky
2016-02-19 4:19 ` Sergey Senozhatsky
2016-02-19 4:46 ` Sergey Senozhatsky
2016-02-19 5:38 ` Sergey Senozhatsky
2016-02-19 5:55 ` Sergey Senozhatsky
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