On Mon, Nov 19, 2001 at 03:52:44PM -0800, Linus Torvalds wrote:
|
| On Mon, 19 Nov 2001, Ken Brownfield wrote:
| >
| > I went straight to the aa patch, and it looks like it either fixes the
| > problem or (because of the side-effects Linus mentioned) otherwise
| > prevents the issue:
|
| So is this pre6aa1, or pre6 + just the watermark patch?
I'm currently using -pre6 with his separately-posted zone-watermark-1
patch. Sorry, I should have been clearer.
| > The machine went into swap immediately when the page cache stopped
| > growing and hovered at 100-400MB. Also, in my experience the page cache
| > will grow until there's only 5ishMB of free RAM, but with the aa patch
| > it looks like it stops at 320MB or maybe 10% of RAM. Was that the aa
| > patch, or part of -pre6?
|
| That was the watermarking. The way Andrea did it, the page cache will
| basically refuse to touch as much of the "normal" page zone, because it
| would prefer to allocate more from highmem..
|
| I think it's excessive to have 320MB free memory, though, that's just
| an insane waste. I suspect that the real number should be somewhere
| between the old behaviour and the new one. You can tweak the behaviour of
| andrea's kernel by changing the "reserved" page numbers, but I'd like to
| hear whether my simpler approach works too..
Yeah, maybe a tiered default would be best, IMHO. 5MB on a 3GB box
does, on the other hand, seem anemic.
| > The Oracle SGA is set to ~522MB, with nothing else running except a
| > couple of sshds, getty, etc. Now that I'm looking, 2.8GB page cache
| > plus 328MB free adds up to about 3.1GB of RAM -- where does the 512MB
| > shared memory segment fit? Is it being swapped out in deference to page
| > cache?
|
| Shared memory actually uses the page cache too, so it will be accounted
| for in the 2.8GB number.
My bad, should have realized.
| Anyway, can you try plain vanilla pre6, with the appended patch? This is
| my suggested simplified version of what Andrea tried to do, and it should
| try to keep only a few extra megs of memory free in the low memory
| regions, not 300+ MB.
|
| (and the profiling would be interesting regardless, but I think Andrea did
| find the real problem, his fix just seems a bit of an overkill ;)
|
| Linus
I'll try this patch ASAP.
Thanks a LOT to all involved,
-- Ken. brownfld@irridia.com| diff -u --recursive --new-file pre6/linux/mm/page_alloc.c linux/mm/page_alloc.c | --- pre6/linux/mm/page_alloc.c Sat Nov 17 19:07:43 2001 | +++ linux/mm/page_alloc.c Mon Nov 19 15:13:36 2001 | @@ -299,29 +299,26 @@ | return page; | } | | -static inline unsigned long zone_free_pages(zone_t * zone, unsigned int order) | -{ | - long free = zone->free_pages - (1UL << order); | - return free >= 0 ? free : 0; | -} | - | /* | * This is the 'heart' of the zoned buddy allocator: | */ | struct page * __alloc_pages(unsigned int gfp_mask, unsigned int order, zonelist_t *zonelist) | { | + unsigned long min; | zone_t **zone, * classzone; | struct page * page; | int freed; | | zone = zonelist->zones; | classzone = *zone; | + min = 1UL << order; | for (;;) { | zone_t *z = *(zone++); | if (!z) | break; | | - if (zone_free_pages(z, order) > z->pages_low) { | + min += z->pages_low; | + if (z->free_pages > min) { | page = rmqueue(z, order); | if (page) | return page; | @@ -334,16 +331,18 @@ | wake_up_interruptible(&kswapd_wait); | | zone = zonelist->zones; | + min = 1UL << order; | for (;;) { | - unsigned long min; | + unsigned long local_min; | zone_t *z = *(zone++); | if (!z) | break; | | - min = z->pages_min; | + local_min = z->pages_min; | if (!(gfp_mask & __GFP_WAIT)) | - min >>= 2; | - if (zone_free_pages(z, order) > min) { | + local_min >>= 2; | + min += local_min; | + if (z->free_pages > min) { | page = rmqueue(z, order); | if (page) | return page; | @@ -376,12 +375,14 @@ | return page; | | zone = zonelist->zones; | + min = 1UL << order; | for (;;) { | zone_t *z = *(zone++); | if (!z) | break; | | - if (zone_free_pages(z, order) > z->pages_min) { | + min += z->pages_min; | + if (z->free_pages > min) { | page = rmqueue(z, order); | if (page) | return page;
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Nov 23 2001 - 21:00:22 EST