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Re: (reiserfs) Re: More on Re: (reiserfs) Reiserfs and ext2fs (was Re: (reiserfs) Sum Benchmarks (these look typical?))
>>>>> "ST" == Stephen C Tweedie <sct@redhat.com> writes:
ST> Hi,
ST> On 30 Jun 1998 19:17:15 -0500, ebiederm+eric@npwt.net (Eric
ST> W. Biederman) said:
>> When either I trace through the code, or a hardware guy convinces me,
>> that it is safe to both write to a page, and do DMA from a page
>> simultaneously I'll believe it.
ST> Read the source code! We already do this. If one process or thread
ST> msync()s a mapped file, its dirty pages get written to disk,
ST> independently of any other processes on the same or other CPUs which
ST> may still have the pages mapped and may still be writing to them. We
ST> don't unmap pages for write; we just mark them non-dirty around all
ST> ptes.
Which is fine but, it still (currently) gets copied to the buffer cache.
As the buffer cache leaves the picture...
Eric