Messages in this thread | | | Date | Wed, 24 Jan 2007 13:53:40 +0800 | From | "Aubrey Li" <> | Subject | Re: [RPC][PATCH 2.6.20-rc5] limit total vfs page cache |
| |
On 1/24/07, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote: > > > Aubrey Li wrote: > > On 1/19/07, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote: > >> Hi Aubrey, > >> > >> I used your patch on my PPC64 box and I do not get expected > >> behavior. As you had requested, I am attaching zoneinfo and meminfo > >> dumps: > >> > >> Please let me know if you need any further data to help me out with > >> the test/experiment. > >> > > > > Although I have no PPC64 box in hand, I think the logic should be the same. > > get_page_from_freelist() is called 5 times in __alloc_pages(). > > > > 1) alloc_flags = ALLOC_WMARK_LOW | ALLOC_PAGECACHE; > > 2) alloc_flags = ALLOC_WMARK_MIN | ALLOC_PAGECACHE; > > We should have the same result on the first two times get_page_from_freelist(). > > > > 3) if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE))) > > && !in_interrupt()) > > alloc_flags = ALLOC_NO_WATERMARKS > > The case on my platform will never enter this branch. If the branch > > occurs on your side, > > The limit will be omitted. Because NO watermark, zone_watermark_ok() > > will not be checked. memory will be allocated directly. > > > > 4)if (likely(did_some_progress)) { > > alloc_flags should include ALLOC_PAGECACHE. > > So we should have the same result on this call. > > > > 5) } else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) { > > alloc_flags = ALLOC_WMARK_HIGH, without ALLOC_PAGECACHE > > > > This branch will not hit on my case. You may need to check it. > > > > If 3) or 5) occurs on your platform, I think you can easily fix it. > > Please confirm it and let me know the result. > > > None of the above condition was the problem in my PPC64 box. I > added __GFP_PAGECACHE flag in pagecache_alloc_cold() and > grab_cache_page_nowait() routines and the reclaim seemed to work. > > --- linux-2.6.20-rc5.orig/include/linux/pagemap.h > +++ linux-2.6.20-rc5/include/linux/pagemap.h > @@ -62,12 +62,12 @@ static inline struct page *__page_cache_ > > static inline struct page *page_cache_alloc(struct address_space *x) > { > - return __page_cache_alloc(mapping_gfp_mask(x)); > + return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_PAGECACHE); > } > > static inline struct page *page_cache_alloc_cold(struct > address_space *x) > { > - return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); > + return > __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD|__GFP_PAGECACHE); > } > > typedef int filler_t(void *, struct page *); > > [snip] > > --- linux-2.6.20-rc5.orig/mm/filemap.c > +++ linux-2.6.20-rc5/mm/filemap.c > @@ -823,7 +823,7 @@ grab_cache_page_nowait(struct address_sp > page_cache_release(page); > return NULL; > } > - page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS); > + page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS | > __GFP_PAGECACHE); > if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) { > page_cache_release(page); > page = NULL; > > > pagecache_alloc_cold() is used in the read-ahead path which was > being called in my case of large file operations. > > --Vaidy > Thanks to point it out. There is another patch on the LKML which I think is better. Checking the zone->max_pagecache in the get_page_from_freelist() is better than checking the watermark in zone_watermark_ok(). Let me know if it works for you.
Thanks, -Aubrey - 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/
| |