| Message ID | 20090901050316.GA4076@in.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
* Ankita Garg <ankita@in.ibm.com> [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 > Any suggestions on improving the patch are most welcome! > > Signed-off-by: Ankita Garg <ankita@in.ibm.com> > > 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 <asm/smp.h> > > 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 > +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? > 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 > + 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. > + } > > return 0; > } > Overall, I think this is the right thing to do, we need to move in this direction.
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. Any suggestions on improving the patch are most welcome! Signed-off-by: Ankita Garg <ankita@in.ibm.com> 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 <asm/smp.h> 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 +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; 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) { + 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; + } return 0; }