Messages in this thread | | | Date | Mon, 18 Jan 1999 11:00:20 +0100 (CET) | From | Andrea Arcangeli <> | Subject | Re: [patch] NEW: arca-vm-21, swapout via shrink_mmap using PG_dirty |
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On 18 Jan 1999, Eric W. Biederman wrote:
> LT> and (b) as you noticed, it increases fragmentation. > > This is only because he didn't implement any kind of request queue. A > fifo queue of pages to write would have keep performance up at current > levels.
Infact I didn't wanted having to alloc more memory in order to free memory (it's something I like to avoid). But the point is that I think that swapping out from shrink_mmap() even if doing ordered I/O is not a win. Try, benchmark and let me know your results, maybe I am wrong. And with a FIFO also shrink_mmap() would change in order to do what swap_out() is doing right now. And btw I think that the fifo could be approssimated to a browse in the swap cache.
> LT> The reason PG_dirty should be a win for shared mappings is: (a) it gets > LT> rid of the file write semaphore problem in a very clean way and > > Nope. Because we can still have some try to write to file X. > That write needs memory, and we try to swapout a mapping of file X. > Unless you believe it implies the write outs then must use a seperate process.
Agreed. I just pointed this out, but maybe I did not understood _where_ we should do the write to disk to reclaim memory.
Andrea Arcangeli
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