From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sat, 14 Feb 2009 08:57:30 +1100 From: Anton Blanchard To: linuxppc-dev@ozlabs.org Subject: [PATCH] Reduce hashtable size when using 64kB pages Message-ID: <20090213215730.GF23273@kryten> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , At the moment we size the hashtable based on 4kB pages / 2, even on a 64kB kernel. This results in a hashtable that is much larger than it needs to be. Grab the real page size and size the hashtable based on that. Note: this only works on non hypervisor machines. Signed-off-by: Anton Blanchard --- diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 8d5b475..f5bc1b2 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -516,7 +516,7 @@ static int __init htab_dt_scan_pftsize(unsigned long node, static unsigned long __init htab_get_table_size(void) { - unsigned long mem_size, rnd_mem_size, pteg_count; + unsigned long mem_size, rnd_mem_size, pteg_count, psize; /* If hash size isn't already provided by the platform, we try to * retrieve it from the device-tree. If it's not there neither, we @@ -534,7 +534,8 @@ static unsigned long __init htab_get_table_size(void) rnd_mem_size <<= 1; /* # pages / 2 */ - pteg_count = max(rnd_mem_size >> (12 + 1), 1UL << 11); + psize = mmu_psize_defs[mmu_virtual_psize].shift; + pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11); return pteg_count << 7; }