Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755791AbZIBFg5 (ORCPT ); Wed, 2 Sep 2009 01:36:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755763AbZIBFg4 (ORCPT ); Wed, 2 Sep 2009 01:36:56 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:39570 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752912AbZIBFgz (ORCPT ); Wed, 2 Sep 2009 01:36:55 -0400 Date: Wed, 2 Sep 2009 11:06:53 +0530 From: Ankita Garg To: Balbir Singh Cc: linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix fake numa on ppc Message-ID: <20090902053653.GA3806@in.ibm.com> Reply-To: Ankita Garg References: <20090901050316.GA4076@in.ibm.com> <20090901055753.GB5563@balbir.in.ibm.com> <20090901092407.GC4076@in.ibm.com> <20090901142729.GA5022@balbir.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090901142729.GA5022@balbir.in.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11181 Lines: 390 Hi Balbir, On Tue, Sep 01, 2009 at 07:57:29PM +0530, Balbir Singh wrote: > * Ankita Garg [2009-09-01 14:54:07]: > > > Hi Balbir, > > > > On Tue, Sep 01, 2009 at 11:27:53AM +0530, Balbir Singh wrote: > > > * Ankita Garg [2009-09-01 10:33:16]: > > > > > > > Hello, > > > > > > > > Below is a patch to fix a couple of issues with fake numa node creation > > > > on ppc: > > > > > > > > 1) Presently, fake nodes could be created such that real numa node > > > > boundaries are not respected. So a node could have lmbs that belong to > > > > different real nodes. > > > > > > > > 2) The cpu association is broken. On a JS22 blade for example, which is > > > > a 2-node numa machine, I get the following: > > > > > > > > # cat /proc/cmdline > > > > root=/dev/sda6 numa=fake=2G,4G,,6G,8G,10G,12G,14G,16G > > > > # cat /sys/devices/system/node/node0/cpulist > > > > 0-3 > > > > # cat /sys/devices/system/node/node1/cpulist > > > > 4-7 > > > > # cat /sys/devices/system/node/node4/cpulist > > > > > > > > # > > > > > > > > So, though the cpus 4-7 should have been associated with node4, they > > > > still belong to node1. The patch works by recording a real numa node > > > > boundary and incrementing the fake node count. At the same time, a > > > > mapping is stored from the real numa node to the first fake node that > > > > gets created on it. > > > > > > > > > > Some details on how you tested it and results before and after would > > > be nice. Please see git commit 1daa6d08d1257aa61f376c3cc4795660877fb9e3 > > > for example > > > > > > > > > > Thanks for the quick review of the patch. Here is some information on > > the testing: > > > > Tested the patch with the following commandlines: > > numa=fake=2G,4G,6G,8G,10G,12G,14G,16G > > numa=fake=3G,6G,10G,16G > > numa=fake=4G > > numa=fake= > > > > For testing if the fake nodes respect the real node boundaries, I added > > some debug printks in the node creation path. Without the patch, for the > > commandline numa=fake=2G,4G,6G,8G,10G,12G,14G,16G, this is what I got: > > > > fake id: 1 nid: 0 > > fake id: 1 nid: 0 > > ... > > fake id: 2 nid: 0 > > fake id: 2 nid: 0 > > ... > > fake id: 2 nid: 0 > > created new fake_node with id 3 > > fake id: 3 nid: 0 > > fake id: 3 nid: 0 > > ... > > fake id: 3 nid: 0 > > fake id: 3 nid: 0 > > fake id: 3 nid: 1 > > fake id: 3 nid: 1 > > ... > > created new fake_node with id 4 > > fake id: 4 nid: 1 > > fake id: 4 nid: 1 > > ... > > > > and so on. So, fake node 3 encompasses real node 0 & 1. Also, > > > > # cat /sys/devices/system/node/node3/meminfo > > Node 0 MemTotal: 2097152 kB > > ... > > # # cat /sys/devices/system/node/node4/meminfo > > Node 0 MemTotal: 2097152 kB > > ... > > > > > > With the patch, I get: > > > > fake id: 1 nid: 0 > > fake id: 1 nid: 0 > > ... > > fake id: 2 nid: 0 > > fake id: 2 nid: 0 > > ... > > fake id: 2 nid: 0 > > created new fake_node with id 3 > > fake id: 3 nid: 0 > > fake id: 3 nid: 0 > > ... > > fake id: 3 nid: 0 > > fake id: 3 nid: 0 > > created new fake_node with id 4 > > fake id: 4 nid: 1 > > fake id: 4 nid: 1 > > ... > > > > and so on. With the patch, the fake node sizes are slightly different > > from that specified by the user. > > > > # cat /sys/devices/system/node/node3/meminfo > > Node 3 MemTotal: 1638400 kB > > ... > > # cat /sys/devices/system/node/node4/meminfo > > Node 4 MemTotal: 458752 kB > > ... > > > > CPU association was tested as mentioned in the previous mail: > > > > Without the patch, > > > > # cat /proc/cmdline > > root=/dev/sda6 numa=fake=2G,4G,,6G,8G,10G,12G,14G,16G > > # cat /sys/devices/system/node/node0/cpulist > > 0-3 > > # cat /sys/devices/system/node/node1/cpulist > > 4-7 > > # cat /sys/devices/system/node/node4/cpulist > > > > # > > > > With the patch, > > > > # cat /proc/cmdline > > root=/dev/sda6 numa=fake=2G,4G,,6G,8G,10G,12G,14G,16G > > # cat /sys/devices/system/node/node0/cpulist > > 0-3 > > # cat /sys/devices/system/node/node1/cpulist > > > > Oh! interesting.. cpuless nodes :) I think we need to fix this in the > longer run and distribute cpus between fake numa nodes of a real node > using some acceptable heuristic. > True. Presently this is broken on both x86 and ppc systems. It would be interesting to find a way to map, for example, 4 cpus to >4 number of fake nodes created from a single real numa node! > > # cat /sys/devices/system/node/node4/cpulist > > 4-7 > > > > > > > > > > Signed-off-by: Ankita Garg > > > > > > > > Index: linux-2.6.31-rc5/arch/powerpc/mm/numa.c > > > > =================================================================== > > > > --- linux-2.6.31-rc5.orig/arch/powerpc/mm/numa.c > > > > +++ linux-2.6.31-rc5/arch/powerpc/mm/numa.c > > > > @@ -26,6 +26,11 @@ > > > > #include > > > > > > > > static int numa_enabled = 1; > > > > +static int fake_enabled = 1; > > > > + > > > > +/* The array maps a real numa node to the first fake node that gets > > > > +created on it */ > > > > > > Coding style is broken > > > > > > > Fixed. > > > > > > +int fake_numa_node_mapping[MAX_NUMNODES]; > > > > > > > > static char *cmdline __initdata; > > > > > > > > @@ -49,14 +54,24 @@ static int __cpuinit fake_numa_create_ne > > > > unsigned long long mem; > > > > char *p = cmdline; > > > > static unsigned int fake_nid; > > > > + static unsigned int orig_nid = 0; > > > > > > Should we call this prev_nid? > > > > > > > Yes, makes sense. > > > > static unsigned long long curr_boundary; > > > > > > > > /* > > > > * Modify node id, iff we started creating NUMA nodes > > > > * We want to continue from where we left of the last time > > > > */ > > > > - if (fake_nid) > > > > + if (fake_nid) { > > > > + if (orig_nid != *nid) { > > > > > > OK, so this is called when the real NUMA node changes - comments would > > > be nice > > > > > > > Thanks, have added the comment. > > > > > > + fake_nid++; > > > > + fake_numa_node_mapping[*nid] = fake_nid; > > > > + orig_nid = *nid; > > > > + *nid = fake_nid; > > > > + return 0; > > > > + } > > > > *nid = fake_nid; > > > > + } > > > > + > > > > /* > > > > * In case there are no more arguments to parse, the > > > > * node_id should be the same as the last fake node id > > > > @@ -440,7 +455,7 @@ static int of_drconf_to_nid_single(struc > > > > */ > > > > static int __cpuinit numa_setup_cpu(unsigned long lcpu) > > > > { > > > > - int nid = 0; > > > > + int nid = 0, new_nid; > > > > struct device_node *cpu = of_get_cpu_node(lcpu, NULL); > > > > > > > > if (!cpu) { > > > > @@ -450,8 +465,15 @@ static int __cpuinit numa_setup_cpu(unsi > > > > > > > > nid = of_node_to_nid_single(cpu); > > > > > > > > + if (fake_enabled && nid) { > > > > + new_nid = fake_numa_node_mapping[nid]; > > > > + if (new_nid > 0) > > > > + nid = new_nid; > > > > + } > > > > + > > > > if (nid < 0 || !node_online(nid)) > > > > nid = any_online_node(NODE_MASK_ALL); > > > > + > > > > out: > > > > map_cpu_to_node(lcpu, nid); > > > > > > > > @@ -1005,8 +1027,11 @@ static int __init early_numa(char *p) > > > > numa_debug = 1; > > > > > > > > p = strstr(p, "fake="); > > > > - if (p) > > > > + if (p) { > > > > cmdline = p + strlen("fake="); > > > > + if (numa_enabled) > > > > + fake_enabled = 1; > > > > > > Have you tried passing just numa=fake= without any commandline? > > > That should enable fake_enabled, but I wonder if that negatively > > > impacts numa_setup_cpu(). I wonder if you should look at cmdline > > > to decide on fake_enabled. > > > > > > > fake_enabled does get set even for numa=fake=. However, it does not > > impact numa_setup_cpu, since fake_numa_node_mapping array would have no > > mapping stored and there is a condition there already to check for the > > value of the mapping. I confirmed this by booting with the above > > parameter as well. > > > > > > + } > > > > > > > > return 0; > > > > } > > > > > > > > > > Overall, I think this is the right thing to do, we need to move in > > > this direction. > > > > > > > Heres the updated patch: > > > > Signed-off-by: Ankita Garg > > > > Index: linux-2.6.31-rc5/arch/powerpc/mm/numa.c > > =================================================================== > > --- linux-2.6.31-rc5.orig/arch/powerpc/mm/numa.c > > +++ linux-2.6.31-rc5/arch/powerpc/mm/numa.c > > @@ -26,6 +26,13 @@ > > #include > > > > static int numa_enabled = 1; > > +static int fake_enabled = 1; > > + > > +/* > > + * The array maps a real numa node to the first fake node that gets > > + * created on it > > + */ > > +int fake_numa_node_mapping[MAX_NUMNODES]; > > > > static char *cmdline __initdata; > > > > @@ -49,14 +56,29 @@ static int __cpuinit fake_numa_create_ne > > unsigned long long mem; > > char *p = cmdline; > > static unsigned int fake_nid; > > + static unsigned int prev_nid = 0; > > static unsigned long long curr_boundary; > > > > /* > > * Modify node id, iff we started creating NUMA nodes > > * We want to continue from where we left of the last time > > */ > > - if (fake_nid) > > + if (fake_nid) { > > + /* > > + * Moved over to the next real numa node, increment fake > > + * node number and store the mapping of the real node to > > + * the fake node > > + */ > > + if (prev_nid != *nid) { > > + fake_nid++; > > + fake_numa_node_mapping[*nid] = fake_nid; > > + prev_nid = *nid; > > + *nid = fake_nid; > > + return 0; > > + } > > *nid = fake_nid; > > + } > > + > > /* > > * In case there are no more arguments to parse, the > > * node_id should be the same as the last fake node id > > @@ -440,7 +462,7 @@ static int of_drconf_to_nid_single(struc > > */ > > static int __cpuinit numa_setup_cpu(unsigned long lcpu) > > { > > - int nid = 0; > > + int nid = 0, new_nid; > > struct device_node *cpu = of_get_cpu_node(lcpu, NULL); > > > > if (!cpu) { > > @@ -450,8 +472,15 @@ static int __cpuinit numa_setup_cpu(unsi > > > > nid = of_node_to_nid_single(cpu); > > > > + if (fake_enabled && nid) { > > + new_nid = fake_numa_node_mapping[nid]; > > + if (new_nid > 0) > > + nid = new_nid; > > + } > > + > > if (nid < 0 || !node_online(nid)) > > nid = any_online_node(NODE_MASK_ALL); > > + > > out: > > map_cpu_to_node(lcpu, nid); > > > > @@ -1005,8 +1034,12 @@ static int __init early_numa(char *p) > > numa_debug = 1; > > > > p = strstr(p, "fake="); > > - if (p) > > + if (p) { > > cmdline = p + strlen("fake="); > > + if (numa_enabled) { > > + fake_enabled = 1; > > + } > > + } > > > > return 0; > > } > > > > > Looks good to me > > > Reviewed-by: Balbir Singh > > > > -- > Balbir -- Regards, Ankita Garg (ankita@in.ibm.com) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India -- 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/