Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH -mm] swsusp: Improve handling of highmem | Date | Mon, 23 Oct 2006 21:25:36 +0200 |
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Hi,
On Monday, 23 October 2006 17:29, Pavel Machek wrote: > Hi! > > > > > Currently swsusp saves the contents of highmem pages by copying them to the > > > > normal zone which is quite inefficient (eg. it requires two normal pages to be > > > > used for saving one highmem page). This may be improved by using highmem > > > > for saving the contents of saveable highmem pages. > > > ... > > > > include/linux/suspend.h | 9 > > > > kernel/power/power.h | 2 > > > > kernel/power/snapshot.c | 841 ++++++++++++++++++++++++++++++++++++------------ > > > > kernel/power/swap.c | 2 > > > > kernel/power/swsusp.c | 53 +-- > > > > kernel/power/user.c | 2 > > > > mm/vmscan.c | 3 > > > > > > Well, I just hoped that highmem would quietly die out... > > > > > > ... > > > > +static struct page *alloc_image_page(gfp_t gfp_mask) { > > > > + struct page *page; > > > > > > { should go on new line. > > > > Ah, yes, thanks. I'll fix this later if you don't mind. > > Ok. > > > > > memory_bm_position_reset(orig_bm); > > > > memory_bm_position_reset(copy_bm); > > > > do { > > > > pfn = memory_bm_next_pfn(orig_bm); > > > > - if (likely(pfn != BM_END_OF_MAP)) { > 1) ############################################## > > > > - struct page *page; > > > > - void *src; > > > > - > > > > - page = pfn_to_page(pfn); > > > > - src = page_address(page); > > > > - page = pfn_to_page(memory_bm_next_pfn(copy_bm)); > > > > - copy_data_page(page_address(page), src); > > > > - } > > > > + if (likely(pfn != BM_END_OF_MAP)) > 2) ############################################## > > > > + copy_data_page(memory_bm_next_pfn(copy_bm), pfn); > > > > } while (pfn != BM_END_OF_MAP); > 3) #################################### > > > > } > > > > > > While(1) and "if (pfn != BM_END_OF_MAP) { ...break; } ? Why do you > > > need to test pfn != BM_END_OF_MAP *three* times? > > > > Why? It's two times, and I don't like while(1) loops, really. > > I see three of them, and while(1) loop is probably best solution > here... "Too scared of break; so I copy conditions"? ;-).
But 1) is being dropped! :-)
In fact 2) goes instead of 1) and 3) stays as it was before.
> > > > @@ -1233,6 +1233,9 @@ out: > > > > } > > > > if (!all_zones_ok) { > > > > cond_resched(); > > > > + > > > > + try_to_freeze(); > > > > + > > > > goto loop_again; > > > > } > > > > > > What is this? > > > > :-) > > > > This is needed because during the resume there likely are no free pages in the > > highmem zone which makes kswapd spin forever, but we have to freeze it before > > the image is restored. > > Could that happen with current code, too? (I'm trying to sense if this > should be merged now as a separate patch).
Certainly not during the resume. It may be possible to be triggered during the suspend (resulting in a suspend failure), but I think that's _extremely_ unlikely.
Greetings, Rafael
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