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Message-Id: <200707232305.12364.nigel@nigel.suspend2.net> Date: Mon, 23 Jul 2007 23:05:12 +1000 From: Nigel Cunningham <nigel@...el.suspend2.net> To: LKML <linux-kernel@...r.kernel.org> Subject: [RFC] [PATCH 0/5] Dynamically allocated pageflags. Hi all. As we all know, pageflags have been a scarce resource for a while now. These patches seek to help address that issue by adding support for a new type of 'dynamically allocated' pageflag. The basic idea is that we use per node & zone bitmaps built out of order zero allocations, to replace bits in page->flags. Bitmaps can be sparse, being populated when a bit on the page is set, and returning zero for all bits in sparse pages. Untested hotplug support is included. This method of storing the data does of course come with a performance hit. I've included some simple timing loops in #ifdef'd code that help quantify that. Interestingly, the new implementation is actually quicker under some circumstances. In cases where the usage pattern involves operating on the flags for a number of pages in succession, the hit involved in getting the struct pages from main memory appears to be greater than that involved in calculating which unsigned long and bit to test. Tested only on UP (x86_64) so far. Regards, Nigel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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