Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756365Ab3INCnx (ORCPT ); Fri, 13 Sep 2013 22:43:53 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:27222 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756004Ab3INCnv (ORCPT ); Fri, 13 Sep 2013 22:43:51 -0400 Message-ID: <5233CD2A.3010504@huawei.com> Date: Sat, 14 Sep 2013 10:42:50 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Tang Chen CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v3 1/5] memblock: Introduce allocation direction to memblock. References: <1379064655-20874-1-git-send-email-tangchen@cn.fujitsu.com> <1379064655-20874-2-git-send-email-tangchen@cn.fujitsu.com> In-Reply-To: <1379064655-20874-2-git-send-email-tangchen@cn.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.74.216] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4664 Lines: 134 Hi Tang, On 2013/9/13 17:30, Tang Chen wrote: > The Linux kernel cannot migrate pages used by the kernel. As a result, kernel > pages cannot be hot-removed. So we cannot allocate hotpluggable memory for > the kernel. > > ACPI SRAT (System Resource Affinity Table) contains the memory hotplug info. > But before SRAT is parsed, memblock has already started to allocate memory > for the kernel. So we need to prevent memblock from doing this. > > In a memory hotplug system, any numa node the kernel resides in should > be unhotpluggable. And for a modern server, each node could have at least > 16GB memory. So memory around the kernel image is highly likely unhotpluggable. > > So the basic idea is: Allocate memory from the end of the kernel image and > to the higher memory. Since memory allocation before SRAT is parsed won't > be too much, it could highly likely be in the same node with kernel image. > > The current memblock can only allocate memory from high address to low. > So this patch introduces the allocation direct to memblock. It could be > used to tell memblock to allocate memory from high to low or from low > to high. > > Signed-off-by: Tang Chen > Reviewed-by: Zhang Yanfei > --- > include/linux/memblock.h | 22 ++++++++++++++++++++++ > mm/memblock.c | 13 +++++++++++++ > 2 files changed, 35 insertions(+), 0 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index 31e95ac..a7d3436 100644 > --- a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -19,6 +19,11 @@ > > #define INIT_MEMBLOCK_REGIONS 128 > > +/* Allocation order. */ s/order/direction/ > +#define MEMBLOCK_DIRECTION_HIGH_TO_LOW 0 > +#define MEMBLOCK_DIRECTION_LOW_TO_HIGH 1 > +#define MEMBLOCK_DIRECTION_DEFAULT MEMBLOCK_DIRECTION_HIGH_TO_LOW > + > struct memblock_region { > phys_addr_t base; > phys_addr_t size; > @@ -35,6 +40,7 @@ struct memblock_type { > }; > > struct memblock { > + int current_direction; /* allocate from higher or lower address */ > phys_addr_t current_limit; > struct memblock_type memory; > struct memblock_type reserved; > @@ -148,6 +154,12 @@ phys_addr_t memblock_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid) > > phys_addr_t memblock_alloc(phys_addr_t size, phys_addr_t align); > > +static inline bool memblock_direction_bottom_up(void) > +{ > + return memblock.current_direction == MEMBLOCK_DIRECTION_LOW_TO_HIGH; > +} > + > + > /* Flags for memblock_alloc_base() amd __memblock_alloc_base() */ > #define MEMBLOCK_ALLOC_ANYWHERE (~(phys_addr_t)0) > #define MEMBLOCK_ALLOC_ACCESSIBLE 0 > @@ -175,6 +187,16 @@ static inline void memblock_dump_all(void) > } > > /** > + * memblock_set_current_direction - Set current allocation direction to allow > + * allocating memory from higher to lower > + * address or from lower to higher address > + * > + * @direction: In which order to allocate memory. Could be s/order/direction/ > + * MEMBLOCK_DIRECTION_{HIGH_TO_LOW|LOW_TO_HIGH} > + */ > +void memblock_set_current_direction(int direction); > + > +/** > * memblock_set_current_limit - Set the current allocation limit to allow > * limiting allocations to what is currently > * accessible during boot > diff --git a/mm/memblock.c b/mm/memblock.c > index 0ac412a..f24ca2e 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -32,6 +32,7 @@ struct memblock memblock __initdata_memblock = { > .reserved.cnt = 1, /* empty dummy entry */ > .reserved.max = INIT_MEMBLOCK_REGIONS, > > + .current_direction = MEMBLOCK_DIRECTION_DEFAULT, > .current_limit = MEMBLOCK_ALLOC_ANYWHERE, > }; > > @@ -995,6 +996,18 @@ void __init_memblock memblock_trim_memory(phys_addr_t align) > } > } > > +void __init_memblock memblock_set_current_direction(int direction) > +{ > + if (direction != MEMBLOCK_DIRECTION_HIGH_TO_LOW && > + direction != MEMBLOCK_DIRECTION_LOW_TO_HIGH) { > + pr_warn("memblock: Failed to set allocation order. " > + "Invalid order type: %d\n", direction); s/order/direction/ > + return; > + } > + > + memblock.current_direction = direction; > +} > + > void __init_memblock memblock_set_current_limit(phys_addr_t limit) > { > memblock.current_limit = limit; -- 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/