Messages in this thread | | | Date | Sat, 19 May 2007 11:21:23 -0700 | From | William Lee Irwin III <> | Subject | Re: [PATCH] MM : alloc_large_system_hash() can free some memory for non power-of-two bucketsize |
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On Fri, May 18, 2007 at 11:54:54AM +0200, Eric Dumazet wrote: > alloc_large_system_hash() is called at boot time to allocate space > for several large hash tables. > Lately, TCP hash table was changed and its bucketsize is not a > power-of-two anymore. > On most setups, alloc_large_system_hash() allocates one big page > (order > 0) with __get_free_pages(GFP_ATOMIC, order). This single > high_order page has a power-of-two size, bigger than the needed size. > We can free all pages that wont be used by the hash table. > On a 1GB i386 machine, this patch saves 128 KB of LOWMEM memory. > TCP established hash table entries: 32768 (order: 6, 393216 bytes)
The proper way to do this is to convert the large system hashtable users to use some data structure / algorithm other than hashing by separate chaining.
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