| Message ID | 20241105172635.2463800-3-namhyung@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | perf lock contention: Symbolize locks using slab cache names (v1) | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Tue, Nov 5, 2024 at 9:27 AM Namhyung Kim <namhyung@kernel.org> wrote: > > Recently the kernel got the kmem_cache iterator to traverse metadata of > slab objects. This can be used to symbolize dynamic locks in a slab. > > The new slab_caches hash map will have the pointer of the kmem_cache as > a key and save the name and a id. The id will be saved in the flags > part of the lock. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/util/bpf_lock_contention.c | 51 +++++++++++++++++++ > .../perf/util/bpf_skel/lock_contention.bpf.c | 28 ++++++++++ > tools/perf/util/bpf_skel/lock_data.h | 12 +++++ > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++ > 4 files changed, 99 insertions(+) > > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c > index 41a1ad08789511c3..a2efd40897bad316 100644 > --- a/tools/perf/util/bpf_lock_contention.c > +++ b/tools/perf/util/bpf_lock_contention.c > @@ -12,12 +12,60 @@ > #include <linux/zalloc.h> > #include <linux/string.h> > #include <bpf/bpf.h> > +#include <bpf/btf.h> > #include <inttypes.h> > > #include "bpf_skel/lock_contention.skel.h" > #include "bpf_skel/lock_data.h" > > static struct lock_contention_bpf *skel; > +static bool has_slab_iter; > + > +static void check_slab_cache_iter(struct lock_contention *con) > +{ > + struct btf *btf = btf__load_vmlinux_btf(); > + s32 ret; > + > + ret = libbpf_get_error(btf); please don't use libbpf_get_error() in new code. I left that API for cases when user might want to support both per-1.0 libbpf and 1.0+, but by now I don't think you should be caring about <1.0 versions. And in 1.0+, you'll get btf == NULL on error, and errno will be set to error. So just check errno directly. > + if (ret) { > + pr_debug("BTF loading failed: %d\n", ret); > + return; > + } > + > + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT); > + if (ret < 0) { > + bpf_program__set_autoload(skel->progs.slab_cache_iter, false); > + pr_debug("slab cache iterator is not available: %d\n", ret); > + goto out; > + } > + > + has_slab_iter = true; > + > + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries); > +out: > + btf__free(btf); > +} > + > +static void run_slab_cache_iter(void) > +{ > + int fd; > + char buf[256]; > + > + if (!has_slab_iter) > + return; > + > + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter)); > + if (fd < 0) { > + pr_debug("cannot create slab cache iter: %d\n", fd); > + return; > + } > + > + /* This will run the bpf program */ > + while (read(fd, buf, sizeof(buf)) > 0) > + continue; > + > + close(fd); > +} > > int lock_contention_prepare(struct lock_contention *con) > { > @@ -109,6 +157,8 @@ int lock_contention_prepare(struct lock_contention *con) > skel->rodata->use_cgroup_v2 = 1; > } > > + check_slab_cache_iter(con); > + > if (lock_contention_bpf__load(skel) < 0) { > pr_err("Failed to load lock-contention BPF skeleton\n"); > return -1; > @@ -304,6 +354,7 @@ static void account_end_timestamp(struct lock_contention *con) > > int lock_contention_start(void) > { > + run_slab_cache_iter(); > skel->bss->enabled = 1; > return 0; > } > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c > index 1069bda5d733887f..fd24ccb00faec0ba 100644 > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c > @@ -100,6 +100,13 @@ struct { > __uint(max_entries, 1); > } cgroup_filter SEC(".maps"); > > +struct { > + __uint(type, BPF_MAP_TYPE_HASH); > + __uint(key_size, sizeof(long)); > + __uint(value_size, sizeof(struct slab_cache_data)); > + __uint(max_entries, 1); > +} slab_caches SEC(".maps"); > + > struct rw_semaphore___old { > struct task_struct *owner; > } __attribute__((preserve_access_index)); > @@ -136,6 +143,8 @@ int perf_subsys_id = -1; > > __u64 end_ts; > > +__u32 slab_cache_id; > + > /* error stat */ > int task_fail; > int stack_fail; > @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp) > return 0; > } > > +SEC("iter/kmem_cache") > +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx) > +{ > + struct kmem_cache *s = ctx->s; > + struct slab_cache_data d; > + > + if (s == NULL) > + return 0; > + > + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; > + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name); > + > + if (d.id >= LCB_F_SLAB_ID_END) > + return 0; > + > + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST); > + return 0; > +} > + > char LICENSE[] SEC("license") = "Dual BSD/GPL"; > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h > index 4f0aae5483745dfa..c15f734d7fc4aecb 100644 > --- a/tools/perf/util/bpf_skel/lock_data.h > +++ b/tools/perf/util/bpf_skel/lock_data.h > @@ -32,9 +32,16 @@ struct contention_task_data { > #define LCD_F_MMAP_LOCK (1U << 31) > #define LCD_F_SIGHAND_LOCK (1U << 30) > > +#define LCB_F_SLAB_ID_SHIFT 16 > +#define LCB_F_SLAB_ID_START (1U << 16) > +#define LCB_F_SLAB_ID_END (1U << 26) > +#define LCB_F_SLAB_ID_MASK 0x03FF0000U > + > #define LCB_F_TYPE_MAX (1U << 7) > #define LCB_F_TYPE_MASK 0x0000007FU > > +#define SLAB_NAME_MAX 28 > + > struct contention_data { > u64 total_time; > u64 min_time; > @@ -55,4 +62,9 @@ enum lock_class_sym { > LOCK_CLASS_RQLOCK, > }; > > +struct slab_cache_data { > + u32 id; > + char name[SLAB_NAME_MAX]; > +}; > + > #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */ > diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > index 4dcad7b682bdee9c..7b81d3173917fdb5 100644 > --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern { > */ > struct rq {}; > > +struct kmem_cache { > + const char *name; > +} __attribute__((preserve_access_index)); > + > +struct bpf_iter__kmem_cache { > + struct kmem_cache *s; > +} __attribute__((preserve_access_index)); > + > #endif // __VMLINUX_H > -- > 2.47.0.199.ga7371fff76-goog > >
Hello, On Wed, Nov 06, 2024 at 11:36:19AM -0800, Andrii Nakryiko wrote: > On Tue, Nov 5, 2024 at 9:27 AM Namhyung Kim <namhyung@kernel.org> wrote: > > > > Recently the kernel got the kmem_cache iterator to traverse metadata of > > slab objects. This can be used to symbolize dynamic locks in a slab. > > > > The new slab_caches hash map will have the pointer of the kmem_cache as > > a key and save the name and a id. The id will be saved in the flags > > part of the lock. > > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > > --- > > tools/perf/util/bpf_lock_contention.c | 51 +++++++++++++++++++ > > .../perf/util/bpf_skel/lock_contention.bpf.c | 28 ++++++++++ > > tools/perf/util/bpf_skel/lock_data.h | 12 +++++ > > tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++ > > 4 files changed, 99 insertions(+) > > > > diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c > > index 41a1ad08789511c3..a2efd40897bad316 100644 > > --- a/tools/perf/util/bpf_lock_contention.c > > +++ b/tools/perf/util/bpf_lock_contention.c > > @@ -12,12 +12,60 @@ > > #include <linux/zalloc.h> > > #include <linux/string.h> > > #include <bpf/bpf.h> > > +#include <bpf/btf.h> > > #include <inttypes.h> > > > > #include "bpf_skel/lock_contention.skel.h" > > #include "bpf_skel/lock_data.h" > > > > static struct lock_contention_bpf *skel; > > +static bool has_slab_iter; > > + > > +static void check_slab_cache_iter(struct lock_contention *con) > > +{ > > + struct btf *btf = btf__load_vmlinux_btf(); > > + s32 ret; > > + > > + ret = libbpf_get_error(btf); > > please don't use libbpf_get_error() in new code. I left that API for > cases when user might want to support both per-1.0 libbpf and 1.0+, > but by now I don't think you should be caring about <1.0 versions. And > in 1.0+, you'll get btf == NULL on error, and errno will be set to > error. So just check errno directly. Oh, great. I'll update the code like below. if (btf == NULL) { pr_debug("BTF loading failed: %s\n", strerror(errno)); return; } Thanks for your review, Namhyung > > > + if (ret) { > > + pr_debug("BTF loading failed: %d\n", ret); > > + return; > > + } > > + > > + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT); > > + if (ret < 0) { > > + bpf_program__set_autoload(skel->progs.slab_cache_iter, false); > > + pr_debug("slab cache iterator is not available: %d\n", ret); > > + goto out; > > + } > > + > > + has_slab_iter = true; > > + > > + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries); > > +out: > > + btf__free(btf); > > +} > > + > > +static void run_slab_cache_iter(void) > > +{ > > + int fd; > > + char buf[256]; > > + > > + if (!has_slab_iter) > > + return; > > + > > + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter)); > > + if (fd < 0) { > > + pr_debug("cannot create slab cache iter: %d\n", fd); > > + return; > > + } > > + > > + /* This will run the bpf program */ > > + while (read(fd, buf, sizeof(buf)) > 0) > > + continue; > > + > > + close(fd); > > +} > > > > int lock_contention_prepare(struct lock_contention *con) > > { > > @@ -109,6 +157,8 @@ int lock_contention_prepare(struct lock_contention *con) > > skel->rodata->use_cgroup_v2 = 1; > > } > > > > + check_slab_cache_iter(con); > > + > > if (lock_contention_bpf__load(skel) < 0) { > > pr_err("Failed to load lock-contention BPF skeleton\n"); > > return -1; > > @@ -304,6 +354,7 @@ static void account_end_timestamp(struct lock_contention *con) > > > > int lock_contention_start(void) > > { > > + run_slab_cache_iter(); > > skel->bss->enabled = 1; > > return 0; > > } > > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c > > index 1069bda5d733887f..fd24ccb00faec0ba 100644 > > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c > > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c > > @@ -100,6 +100,13 @@ struct { > > __uint(max_entries, 1); > > } cgroup_filter SEC(".maps"); > > > > +struct { > > + __uint(type, BPF_MAP_TYPE_HASH); > > + __uint(key_size, sizeof(long)); > > + __uint(value_size, sizeof(struct slab_cache_data)); > > + __uint(max_entries, 1); > > +} slab_caches SEC(".maps"); > > + > > struct rw_semaphore___old { > > struct task_struct *owner; > > } __attribute__((preserve_access_index)); > > @@ -136,6 +143,8 @@ int perf_subsys_id = -1; > > > > __u64 end_ts; > > > > +__u32 slab_cache_id; > > + > > /* error stat */ > > int task_fail; > > int stack_fail; > > @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp) > > return 0; > > } > > > > +SEC("iter/kmem_cache") > > +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx) > > +{ > > + struct kmem_cache *s = ctx->s; > > + struct slab_cache_data d; > > + > > + if (s == NULL) > > + return 0; > > + > > + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; > > + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name); > > + > > + if (d.id >= LCB_F_SLAB_ID_END) > > + return 0; > > + > > + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST); > > + return 0; > > +} > > + > > char LICENSE[] SEC("license") = "Dual BSD/GPL"; > > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h > > index 4f0aae5483745dfa..c15f734d7fc4aecb 100644 > > --- a/tools/perf/util/bpf_skel/lock_data.h > > +++ b/tools/perf/util/bpf_skel/lock_data.h > > @@ -32,9 +32,16 @@ struct contention_task_data { > > #define LCD_F_MMAP_LOCK (1U << 31) > > #define LCD_F_SIGHAND_LOCK (1U << 30) > > > > +#define LCB_F_SLAB_ID_SHIFT 16 > > +#define LCB_F_SLAB_ID_START (1U << 16) > > +#define LCB_F_SLAB_ID_END (1U << 26) > > +#define LCB_F_SLAB_ID_MASK 0x03FF0000U > > + > > #define LCB_F_TYPE_MAX (1U << 7) > > #define LCB_F_TYPE_MASK 0x0000007FU > > > > +#define SLAB_NAME_MAX 28 > > + > > struct contention_data { > > u64 total_time; > > u64 min_time; > > @@ -55,4 +62,9 @@ enum lock_class_sym { > > LOCK_CLASS_RQLOCK, > > }; > > > > +struct slab_cache_data { > > + u32 id; > > + char name[SLAB_NAME_MAX]; > > +}; > > + > > #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */ > > diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > > index 4dcad7b682bdee9c..7b81d3173917fdb5 100644 > > --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > > +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h > > @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern { > > */ > > struct rq {}; > > > > +struct kmem_cache { > > + const char *name; > > +} __attribute__((preserve_access_index)); > > + > > +struct bpf_iter__kmem_cache { > > + struct kmem_cache *s; > > +} __attribute__((preserve_access_index)); > > + > > #endif // __VMLINUX_H > > -- > > 2.47.0.199.ga7371fff76-goog > > > >
diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index 41a1ad08789511c3..a2efd40897bad316 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -12,12 +12,60 @@ #include <linux/zalloc.h> #include <linux/string.h> #include <bpf/bpf.h> +#include <bpf/btf.h> #include <inttypes.h> #include "bpf_skel/lock_contention.skel.h" #include "bpf_skel/lock_data.h" static struct lock_contention_bpf *skel; +static bool has_slab_iter; + +static void check_slab_cache_iter(struct lock_contention *con) +{ + struct btf *btf = btf__load_vmlinux_btf(); + s32 ret; + + ret = libbpf_get_error(btf); + if (ret) { + pr_debug("BTF loading failed: %d\n", ret); + return; + } + + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT); + if (ret < 0) { + bpf_program__set_autoload(skel->progs.slab_cache_iter, false); + pr_debug("slab cache iterator is not available: %d\n", ret); + goto out; + } + + has_slab_iter = true; + + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries); +out: + btf__free(btf); +} + +static void run_slab_cache_iter(void) +{ + int fd; + char buf[256]; + + if (!has_slab_iter) + return; + + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter)); + if (fd < 0) { + pr_debug("cannot create slab cache iter: %d\n", fd); + return; + } + + /* This will run the bpf program */ + while (read(fd, buf, sizeof(buf)) > 0) + continue; + + close(fd); +} int lock_contention_prepare(struct lock_contention *con) { @@ -109,6 +157,8 @@ int lock_contention_prepare(struct lock_contention *con) skel->rodata->use_cgroup_v2 = 1; } + check_slab_cache_iter(con); + if (lock_contention_bpf__load(skel) < 0) { pr_err("Failed to load lock-contention BPF skeleton\n"); return -1; @@ -304,6 +354,7 @@ static void account_end_timestamp(struct lock_contention *con) int lock_contention_start(void) { + run_slab_cache_iter(); skel->bss->enabled = 1; return 0; } diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c index 1069bda5d733887f..fd24ccb00faec0ba 100644 --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -100,6 +100,13 @@ struct { __uint(max_entries, 1); } cgroup_filter SEC(".maps"); +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(long)); + __uint(value_size, sizeof(struct slab_cache_data)); + __uint(max_entries, 1); +} slab_caches SEC(".maps"); + struct rw_semaphore___old { struct task_struct *owner; } __attribute__((preserve_access_index)); @@ -136,6 +143,8 @@ int perf_subsys_id = -1; __u64 end_ts; +__u32 slab_cache_id; + /* error stat */ int task_fail; int stack_fail; @@ -563,4 +572,23 @@ int BPF_PROG(end_timestamp) return 0; } +SEC("iter/kmem_cache") +int slab_cache_iter(struct bpf_iter__kmem_cache *ctx) +{ + struct kmem_cache *s = ctx->s; + struct slab_cache_data d; + + if (s == NULL) + return 0; + + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; + bpf_probe_read_kernel_str(d.name, sizeof(d.name), s->name); + + if (d.id >= LCB_F_SLAB_ID_END) + return 0; + + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST); + return 0; +} + char LICENSE[] SEC("license") = "Dual BSD/GPL"; diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 4f0aae5483745dfa..c15f734d7fc4aecb 100644 --- a/tools/perf/util/bpf_skel/lock_data.h +++ b/tools/perf/util/bpf_skel/lock_data.h @@ -32,9 +32,16 @@ struct contention_task_data { #define LCD_F_MMAP_LOCK (1U << 31) #define LCD_F_SIGHAND_LOCK (1U << 30) +#define LCB_F_SLAB_ID_SHIFT 16 +#define LCB_F_SLAB_ID_START (1U << 16) +#define LCB_F_SLAB_ID_END (1U << 26) +#define LCB_F_SLAB_ID_MASK 0x03FF0000U + #define LCB_F_TYPE_MAX (1U << 7) #define LCB_F_TYPE_MASK 0x0000007FU +#define SLAB_NAME_MAX 28 + struct contention_data { u64 total_time; u64 min_time; @@ -55,4 +62,9 @@ enum lock_class_sym { LOCK_CLASS_RQLOCK, }; +struct slab_cache_data { + u32 id; + char name[SLAB_NAME_MAX]; +}; + #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */ diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h index 4dcad7b682bdee9c..7b81d3173917fdb5 100644 --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern { */ struct rq {}; +struct kmem_cache { + const char *name; +} __attribute__((preserve_access_index)); + +struct bpf_iter__kmem_cache { + struct kmem_cache *s; +} __attribute__((preserve_access_index)); + #endif // __VMLINUX_H
Recently the kernel got the kmem_cache iterator to traverse metadata of slab objects. This can be used to symbolize dynamic locks in a slab. The new slab_caches hash map will have the pointer of the kmem_cache as a key and save the name and a id. The id will be saved in the flags part of the lock. Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/util/bpf_lock_contention.c | 51 +++++++++++++++++++ .../perf/util/bpf_skel/lock_contention.bpf.c | 28 ++++++++++ tools/perf/util/bpf_skel/lock_data.h | 12 +++++ tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++ 4 files changed, 99 insertions(+)