Re: [PATCH v1 2/2] powerpc/pseries: Add debugfs interface to retrieve VPHN info
From: Naveen N. Rao <hidden>
Date: 2018-12-13 10:55:14
Hi Michael, Naveen N. Rao wrote:
Add debugfs interface to retrieve associativity information for lpar vcpus (debugfs/vphn/lpar) and the hypervisor cpus (debugfs/vphn/hyp). This information is useful to derive various metrics, including the vcpu dispatch statistics in a SPLPAR environment.
Any thoughts on this approach vs. adding a tracepoint? Thanks, Naveen
quoted hunk
Signed-off-by: Naveen N. Rao <redacted> --- arch/powerpc/mm/numa.c | 105 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+)diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index 6677a578f18d..f0b0e87016e6 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c@@ -40,6 +40,7 @@ #include <asm/setup.h> #include <asm/vdso.h> #include <asm/drmem.h> +#include <asm/debugfs.h> static int numa_enabled = 1;@@ -1089,6 +1090,107 @@ static long hcall_vphn(unsigned long cpu, u64 flags, __be32 *associativity) return rc; } +#ifdef CONFIG_DEBUG_FS +static ssize_t vphn_lpar_cpu_file_read(struct file *filp, char __user *buf, + size_t len, loff_t *pos) +{ + int cpu = (long)filp->private_data; + __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0}; + int hwcpu = get_hard_smp_processor_id(cpu); + long int rc; + + if (len != sizeof(associativity)) + return -EINVAL; + + rc = hcall_vphn(hwcpu, 1, associativity); + if (rc) + return -EFAULT; + + rc = copy_to_user(buf, &associativity, sizeof(associativity)); + if (rc) + return -EFAULT; + + return sizeof(associativity); +} + +static ssize_t vphn_hyp_cpu_file_read(struct file *filp, char __user *buf, + size_t len, loff_t *pos) +{ + int cpu = (long)filp->private_data; + __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0}; + long int rc; + + if (len != sizeof(associativity)) + return -EINVAL; + + rc = hcall_vphn(cpu, 2, associativity); + if (rc) + return -EFAULT; + + rc = copy_to_user(buf, &associativity, sizeof(associativity)); + if (rc) + return -EFAULT; + + return sizeof(associativity); +} + +static const struct file_operations vphn_lpar_cpu_fops = { + .open = simple_open, + .read = vphn_lpar_cpu_file_read, + .llseek = no_llseek, +}; + +static const struct file_operations vphn_hyp_cpu_fops = { + .open = simple_open, + .read = vphn_hyp_cpu_file_read, + .llseek = no_llseek, +}; + +static int debug_init_vphn_entries(void) +{ + struct dentry *vphn_dir, *vphn_lpar_dir, *vphn_hyp_dir; + struct dentry *vphn_lpar_cpu_file, *vphn_hyp_cpu_file; + long cpu; + char name[10]; + + if (!firmware_has_feature(FW_FEATURE_SPLPAR)) + return 0; + + vphn_dir = debugfs_create_dir("vphn", powerpc_debugfs_root); + if (!vphn_dir) { + pr_warn("%s: can't create vphn debugfs root dir\n", __func__); + return -ENOMEM; + } + + vphn_lpar_dir = debugfs_create_dir("lpar", vphn_dir); + vphn_hyp_dir = debugfs_create_dir("hyp", vphn_dir); + if (!vphn_lpar_dir || !vphn_hyp_dir) { + pr_warn("%s: can't create vphn dir\n", __func__); + goto err_remove_dir; + } + + for_each_possible_cpu(cpu) { + sprintf(name, "cpu-%ld", cpu); + vphn_lpar_cpu_file = debugfs_create_file(name, 0400, + vphn_lpar_dir, (void *)cpu, &vphn_lpar_cpu_fops); + vphn_hyp_cpu_file = debugfs_create_file(name, 0400, + vphn_hyp_dir, (void *)cpu, &vphn_hyp_cpu_fops); + if (!vphn_lpar_cpu_file || !vphn_hyp_cpu_file) { + pr_warn("%s: can't create vphn cpu file\n", __func__); + goto err_remove_dir; + } + } + + return 0; + +err_remove_dir: + debugfs_remove_recursive(vphn_dir); + return -ENOMEM; +} +#else +static int debug_init_vphn_entries(void) { return 0; } +#endif /* CONFIG_DEBUG_FS */ + /* * Change polling interval for associativity changes. */@@ -1619,6 +1721,9 @@ static int topology_update_init(void) if (!proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops)) return -ENOMEM; + if (!debug_init_vphn_entries()) + return -ENOMEM; + topology_inited = 1; return 0; }-- 2.19.2