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.
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