Very Computer

by **Andrew Morto** » Thu, 21 Mar 2002 13:20:08

Last one.

Don't bother checking for active pages in the swapout path.

Not sure about this one. Clearly the page isn't *likely* to be on the
active list, because the caller found it on the inactive list. But I
don't see any locking which would prevent the page from getting bumped
up to the active list in the meanwhile.

Needs more explanation.

=====================================

--- 2.4.19-pre3/mm/vmscan.c~aa-200-active_page_swapout Tue Mar 19 19:49:04 2002

return 0;
}

- /* Don't bother unmapping pages that are active */
- if (PageActive(page))
- return 0;
-
/* Don't bother replenishing zones not under pressure.. */
if (!memclass(page_zone(page), classzone))
return 0;

-
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by **Rik van Rie** » Thu, 21 Mar 2002 23:00:22

> Don't bother checking for active pages in the swapout path.

> Not sure about this one. Clearly the page isn't *likely* to be on the
> active list, because the caller found it on the inactive list.

Mmmm nope.

The caller of swap_out (shrink_caches) may have been scanning the
inactive list, but swap_out itself scans the page tables.

This means it can encounter all kinds of pages, active, inactive
and even reserved pages.

> --- 2.4.19-pre3/mm/vmscan.c~aa-200-active_page_swapout Tue Mar 19 19:49:04 2002
> +++ 2.4.19-pre3-akpm/mm/vmscan.c Tue Mar 19 19:49:04 2002

> return 0;
> }

> - /* Don't bother unmapping pages that are active */
> - if (PageActive(page))
> - return 0;
> -
> /* Don't bother replenishing zones not under pressure.. */
> if (!memclass(page_zone(page), classzone))
> return 0;

> -
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in

> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

Rik
--
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by **Andrew Morto** » Fri, 22 Mar 2002 04:30:14

> > Don't bother checking for active pages in the swapout path.

> > Not sure about this one. Clearly the page isn't *likely* to be on the
> > active list, because the caller found it on the inactive list.

> Mmmm nope.

> The caller of swap_out (shrink_caches) may have been scanning the
> inactive list, but swap_out itself scans the page tables.

> This means it can encounter all kinds of pages, active, inactive
> and even reserved pages.

good point :)

So what does the patch do?

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