Date: Wed, 19 Feb 2014 17:29:52 -0800 From: George Kola <georgekola@gmail.com> To: freebsd-hackers@freebsd.org Subject: Question about ZFS arc cache and page cache Message-ID: <FDC8515A-BD89-482A-8003-002060A702E4@gmail.com>
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I have a question about what happens when a file on a ZFS filesystem is = mmaped into memory. I traced it on illumos and found that the file pages = made it into the ARC cache and then I got a copy of it in page cache = which was then mapped to my address space. Another process mapping the = same file got the same page from the page cache. (I used mdb and = converting virtual address to physical address to see if the pages were = the same) . I was wondering if FreeBSD does the same copy or if the physical pages = in ARC can be used for mmap without requiring a copy. The reason for = this question is that we are currently on illumos and are considering = moving to FreeBSD and are evaluating the pros and cons. Thanks, George
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