From: zhouxianrong <zhouxianrong@huawei.com>
To: Matthew Wilcox <willy@infradead.org>, Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
<linux-kernel@vger.kernel.org>, <linux-arch@vger.kernel.org>,
<sergey.senozhatsky@gmail.com>, <iamjoonsoo.kim@lge.com>,
<ngupta@vflare.org>, <zhouxiyu@huawei.com>, <weidu.du@huawei.com>,
<zhangshiming5@huawei.com>, <Mi.Sophia.Wang@huawei.com>,
<won.ho.park@huawei.com>
Subject: Re: memfill
Date: Tue, 7 Feb 2017 10:47:51 +0800 [thread overview]
Message-ID: <069b76a3-fe60-5cb1-46dd-fac977d7daf9@huawei.com> (raw)
In-Reply-To: <20170206144902.GH2267@bombadil.infradead.org>
On 2017/2/6 22:49, Matthew Wilcox wrote:
>
> [adding linux-arch to see if anyone there wants to do an optimised
> version of memfill for their CPU]
>
> On Mon, Feb 06, 2017 at 12:16:44AM +0900, Minchan Kim wrote:
>> +static inline void zram_fill_page(char *ptr, unsigned long len,
>> + unsigned long value)
>> +{
>> + int i;
>> + unsigned long *page = (unsigned long *)ptr;
>> +
>> + WARN_ON_ONCE(!IS_ALIGNED(len, sizeof(unsigned long)));
>> +
>> + if (likely(value == 0)) {
>> + memset(ptr, 0, len);
>> + } else {
>> + for (i = 0; i < len / sizeof(*page); i++)
>> + page[i] = value;
>> + }
>> +}
>
> I would suggest:
>
> #ifndef __HAVE_ARCH_MEMFILL
> /**
> * memfill - Fill a region of memory with the given value
> * @s: Pointer to the start of the region.
> * @v: The word to fill the region with.
> * @n: The size of the region.
> *
> * Differs from memset() in that it fills with an unsigned long instead of
> * a byte. The pointer and the size must be aligned to unsigned long.
> */
> void memfill(unsigned long *s, unsigned long v, size_t n)
> {
> WARN_ON_ONCE(!IS_ALIGNED(n, sizeof(v)));
>
> if (likely(v == 0)) {
> memset(s, 0, n);
> } else {
> while (n) {
> *s++ = v;
> n -= sizeof(v);
> }
> }
> }
> EXPORT_SYMBOL(memfill);
> #endif
>
> (I would also suggest this move to lib/string.c and architectures be
> given the opportunity to provide an optimised version of memfill).
>
good idea, i hope kernel could support family functions like memfill/memset_long
in lib. but this is beyond zram scope.
>
> .
>
next prev parent reply other threads:[~2017-02-07 2:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-05 15:16 [PATCH v4] zram: extend zero pages to same element pages Minchan Kim
2017-02-06 14:49 ` memfill Matthew Wilcox
2017-02-07 2:47 ` zhouxianrong [this message]
2017-02-07 4:59 ` memfill Minchan Kim
2017-02-07 19:07 ` memfill James Bottomley
2017-02-08 18:04 ` memfill Matthew Wilcox
2017-02-08 21:01 ` memfill James Bottomley
2017-02-08 21:54 ` memfill Matthew Wilcox
2017-02-07 6:57 ` [PATCH v4] zram: extend zero pages to same element pages Minchan Kim
2017-02-07 9:40 ` memfill David Howells
2017-02-07 17:22 ` memfill Matthew Wilcox
2017-02-07 17:29 ` memfill David Howells
2017-02-07 19:03 ` memfill Matthew Wilcox
2017-03-11 14:56 ` memfill v2 now with ARM and x86 implementations Matthew Wilcox
2017-03-13 5:17 ` Minchan Kim
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