Messages in this thread | | | Date | Mon, 08 Sep 2008 18:31:22 +0800 | From | Li Yu <> | Subject | Re: [PATCH] VM: Implements the swap-out page-clustering technique |
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Li Yu 写道: > hamidreza jahanjou 写道: >> 2008/9/8, Li Yu <raise.sail@gmail.com>: >> >>> And the linear searching for whole address space of a vma is not good >>> idea too, really. >>> >>> >>>> + if (!page_allowed_in_cluster(cursor_page, ci)) >>>> + continue; >>>> >>>> >> >> Thank you for the review and comments. You are right in that searching >> the whole process address space is not a good idea. The idea is to >> make the scan range flexible, thus normally, assuming that the code >> has been well-tuned, only a very limited number of VMA's are scanned. >> >> In general, i think that the cluster size and the scan range should be >> tuned depending on the backing storage characteristics and the >> low-on-memory severity. Like any VM code, this one needs tuning. >> >> BTW, the code could be implemented much more elegantly if the VMA's >> were connected using a doubly-linked list. I wonder if there are >> enought other codes with the same situation to justify making it >> doubly-linked. >> > > You are welcome! > > I think that scanning one vma each task is enough. > > The goal of swapoutclustering is to reduce disk heads movement while > swapping in, it is based on space/time locality. I think that > different vmas implied different using pattern, which also means they > have different in program locality. Therefore, I think scanning multi > vmas per task is not a good idea. > > Maybe, we need a page cache searching like for anonymous mapping > instead of *linear* searching in each vma. > > I also have an uncompleted implementation for this feature ^_^ > > Good luck. >
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