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
--
You never change things by fighting the existing reality.
R. Buckminster Fuller
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