From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Joonsoo Kim <js1304@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: Fri, 19 Feb 2016 14:55:07 +0900 [thread overview]
Message-ID: <20160219055507.GC16230@swordfish> (raw)
In-Reply-To: <20160219053814.GB16230@swordfish>
On (02/19/16 14:38), Sergey Senozhatsky wrote:
[..]
> #define OBJ_ALLOCATED_TAG 1
> #define OBJ_TAG_BITS 1
> #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
> #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
>
> #define ZS_MIN_ALLOC_SIZE \
> MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
[..]
> -- on 32 bit system, PAGE_SHIFT 12
>
> ZS_MAX_PAGES_PER_ZSPAGE 1 << 4 16
> OBJ_INDEX_BITS (32 - (32 - 12) - 1) 11
> OBJ_INDEX_MASK ((1 << (32 - (32 - 12) - 1)) - 1) 2047
> ZS_MIN_ALLOC_SIZE MAX(32, ((1 << 4) << 12 >> (32 - (32 - 12) - 1))) 32
>
> -- on 64 bit system, PAGE_SHIFT 12
>
> ZS_MAX_PAGES_PER_ZSPAGE 1 << 4 16
> OBJ_INDEX_BITS (64 - (64 - 12) - 1) 11
> OBJ_INDEX_MASK ((1 << (64 - (64 - 12) - 1)) - 1) 2047
> ZS_MIN_ALLOC_SIZE MAX(32, ((1 << 4) << 12 >> (64 - (64 - 12) - 1))) 32
even if it's missing "HANDLE_PIN_BIT 0", it's still OBJ_INDEX_BITS 10,
2<<10 should be enough to keep 32 bytes class around.
> -- on 64 bit system, PAGE_SHIFT 14
>
> ZS_MAX_PAGES_PER_ZSPAGE 1 << 4 16
> OBJ_INDEX_BITS (64 - (64 - 14) - 1) 13
> OBJ_INDEX_MASK ((1 << (64 - (64 - 14) - 1)) - 1) 8191
> ZS_MIN_ALLOC_SIZE MAX(32, ((1 << 4) << 14 >> (64 - (64 - 14) - 1))) 32
OBJ_INDEX_BITS 2<<12 still looks to be good enough.
-ss
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prev parent reply other threads:[~2016-02-19 5:53 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
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 [this message]
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