On 03/26/2015 06:00 AM, Elliott, Robert (Server Storage) wrote: > > >> -----Original Message----- >> From: linux-kernel-ow...@vger.kernel.org [mailto:linux-kernel- >> ow...@vger.kernel.org] On Behalf Of Andy Lutomirski >> Sent: Wednesday, March 18, 2015 1:07 PM >> To: Boaz Harrosh >> Cc: Matthew Wilcox; Ross Zwisler; X86 ML; Thomas Gleixner; Dan Williams; >> Ingo Molnar; Roger C. Pao; linux-nvdimm; linux-kernel; H. Peter Anvin; >> Christoph Hellwig >> Subject: Re: [PATCH 1/8] pmem: Initial version of persistent memory driver >> >> On Mar 9, 2015 8:20 AM, "Boaz Harrosh" <b...@plexistor.com> wrote: >>> >>> On 03/06/2015 01:03 AM, Andy Lutomirski wrote: >>> <> >>>> >>>> I think it would be nice to have control over the caching mode. >>>> Depending on the application, WT or UC could make more sense. >>>> >>> >>> Patches are welcome. say >>> map=sss@aaa:WT,sss@aaa:CA, ... >>> >>> But for us, with direct_access(), all benchmarks show a slight advantage >>> for the cached mode. >> >> I'm sure cached is faster. The question is: who flushes the cache? >> >> --Andy > > Nobody. > > Therefore, pmem as currently proposed (mapping the memory with > ioremap_cache, which uses _PAGE_CACHE_MODE_WB) is unsafe unless the > system is doing something special to ensure L1, L2, and L3 caches are > flushed on power loss. > > I think pmem needs to map the memory as UC or WT by default, providing > WB and WC only as an option for users confident that those attributes > are safe to use in their system. > > Even using UC or WT presumes that ADR is in place. >
I will add command line options for these modes per range. (Unless you care to send a patch before me) Thanks this is a good idea Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
