From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e17.ny.us.ibm.com (e17.ny.us.ibm.com [129.33.205.207]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 135141A06EA for ; Wed, 10 Feb 2016 20:01:10 +1100 (AEDT) Received: from localhost by e17.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 10 Feb 2016 04:01:08 -0500 Received: from b01cxnp22034.gho.pok.ibm.com (b01cxnp22034.gho.pok.ibm.com [9.57.198.24]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 244B66E8048 for ; Wed, 10 Feb 2016 03:47:58 -0500 (EST) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u1A9168G26935464 for ; Wed, 10 Feb 2016 09:01:06 GMT Received: from d01av03.pok.ibm.com (localhost [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u1A915vi006620 for ; Wed, 10 Feb 2016 04:01:05 -0500 From: "Aneesh Kumar K.V" To: David Gibson , mpe@ellerman.id.au, paulus@samba.org, benh@kernel.crashing.org Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, David Gibson Subject: Re: [PATCH 4/4] powerpc/mm: Split hash page table sizing heuristic into a helper In-Reply-To: <1454988763-5580-5-git-send-email-david@gibson.dropbear.id.au> References: <1454988763-5580-1-git-send-email-david@gibson.dropbear.id.au> <1454988763-5580-5-git-send-email-david@gibson.dropbear.id.au> Date: Wed, 10 Feb 2016 14:31:00 +0530 Message-ID: <871t8lx7lf.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , David Gibson writes: > htab_get_table_size() either retrieve the size of the hash page table (HPT) > from the device tree - if the HPT size is determined by firmware - or > uses a heuristic to determine a good size based on RAM size if the kernel > is responsible for allocating the HPT. > > To support a PAPR extension allowing resizing of the HPT, we're going to > want the memory size -> HPT size logic elsewhere, so split it out into a > helper function. > Reviewed-by: Aneesh Kumar K.V > Signed-off-by: David Gibson > --- > arch/powerpc/include/asm/mmu-hash64.h | 3 +++ > arch/powerpc/mm/hash_utils_64.c | 32 +++++++++++++++++++------------- > 2 files changed, 22 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h > index 7352d3f..cf070fd 100644 > --- a/arch/powerpc/include/asm/mmu-hash64.h > +++ b/arch/powerpc/include/asm/mmu-hash64.h > @@ -607,6 +607,9 @@ static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize) > context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1; > return get_vsid(context, ea, ssize); > } > + > +unsigned htab_shift_for_mem_size(unsigned long mem_size); > + > #endif /* __ASSEMBLY__ */ > > #endif /* _ASM_POWERPC_MMU_HASH64_H_ */ > diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c > index fdcf9d1..da5d279 100644 > --- a/arch/powerpc/mm/hash_utils_64.c > +++ b/arch/powerpc/mm/hash_utils_64.c > @@ -611,10 +611,26 @@ static int __init htab_dt_scan_pftsize(unsigned long node, > return 0; > } > > -static unsigned long __init htab_get_table_size(void) > +unsigned htab_shift_for_mem_size(unsigned long mem_size) > { > - unsigned long mem_size, rnd_mem_size, pteg_count, psize; > + unsigned memshift = __ilog2(mem_size); > + unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift; > + unsigned pteg_shift; > + > + /* round mem_size up to next power of 2 */ > + if ((1UL << memshift) < mem_size) > + memshift += 1; > + > + /* aim for 2 pages / pteg */ > + pteg_shift = memshift - (pshift + 1); > + > + /* 2^11 PTEGS / 2^18 bytes is the minimum htab size permitted > + * by the architecture */ > + return max(pteg_shift + 7, 18U); > +} > > +static unsigned long __init htab_get_table_size(void) > +{ > /* 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 > * calculate it now based on the total RAM size > @@ -624,17 +640,7 @@ static unsigned long __init htab_get_table_size(void) > if (ppc64_pft_size) > return 1UL << ppc64_pft_size; > > - /* round mem_size up to next power of 2 */ > - mem_size = memblock_phys_mem_size(); > - rnd_mem_size = 1UL << __ilog2(mem_size); > - if (rnd_mem_size < mem_size) > - rnd_mem_size <<= 1; > - > - /* # pages / 2 */ > - psize = mmu_psize_defs[mmu_virtual_psize].shift; > - pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11); > - > - return pteg_count << 7; > + return 1UL << htab_shift_for_mem_size(memblock_phys_mem_size()); > } > > #ifdef CONFIG_MEMORY_HOTPLUG > -- > 2.5.0