[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6 1/8] mm: Place unscrubbed pages at the end of pagelist
>>> Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> 08/07/17 4:56 PM >>> >On 08/07/2017 10:37 AM, Jan Beulich wrote: >>>>>> Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> 08/07/17 4:16 PM >>> >>> On 08/06/2017 01:41 PM, Jan Beulich wrote: >>>>>>> Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> 08/04/17 7:03 PM >>> >>>>> + /* See if any of the pages indeed need scrubbing. */ >>>>> + if ( first_dirty != INVALID_DIRTY_IDX ) >>>>> + { >>>>> + if ( (1U << cur_order) > first_dirty ) >>>>> + { >>>>> + for ( i = first_dirty ; i < (1U << cur_order); >>>>> i++ ) >>>>> + if ( test_bit(_PGC_need_scrub, >>>>> + &cur_head[i].count_info) ) >>>>> + { >>>>> + idx = i; >>>>> + break; >>>>> + } >>>> Why again do you need to look through all the pages here, rather than >>>> simply marking the chunks as needing scrubbing simply based on first_dirty? >>>> It seems to me that I've asked this before, which is a good indication that >>>> such special behavior would better have a comment attached. >>> We want to make sure that there are in fact dirty pages in the >>> (sub-)buddy: first_dirty is only a hint there *may be* some. >> But why is that needed? Iirc you don't go to such length when splitting a >> buddy during allocation. > >I felt that allocation is more time-critical and so I decided against >trying to be "neat" as far as tracking dirty pages exactly. I'd suggest to use the simpler approach here too, if the more involved one isn't needed for correctness. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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