Messages in this thread | | | Subject | Re: [v3 0/9] parallelized "struct page" zeroing | From | Pasha Tatashin <> | Date | Fri, 12 May 2017 13:24:52 -0400 |
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On 05/12/2017 12:57 PM, David Miller wrote: > From: Pasha Tatashin <pasha.tatashin@oracle.com> > Date: Thu, 11 May 2017 16:59:33 -0400 > >> We should either keep memset() only for deferred struct pages as what >> I have in my patches. >> >> Another option is to add a new function struct_page_clear() which >> would default to memset() and to something else on platforms that >> decide to optimize it. >> >> On SPARC it would call STBIs, and we would do one membar call after >> all "struct pages" are initialized. > > No membars will be performed for single individual page struct clear, > the cutoff to use the STBI is larger than that. >
Right now it is larger, but what I suggested is to add a new optimized routine just for this case, which would do STBI for 64-bytes but without membar (do membar at the end of memmap_init_zone() and deferred_init_memmap()
#define struct_page_clear(page) \ __asm__ __volatile__( \ "stxa %%g0, [%0]%2\n" \ "stxa %%xg0, [%0 + %1]%2\n" \ : /* No output */ \ : "r" (page), "r" (0x20), "i"(ASI_BLK_INIT_QUAD_LDD_P))
And insert it into __init_single_page() instead of memset()
The final result is 4.01s/T which is even faster compared to current 4.97s/T
Pasha
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