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Date: Mon, 11 May 2020 17:35:28 -0700 From: Yonghong Song <yhs@...com> To: Lorenzo Bianconi <lorenzo@...nel.org>, <bpf@...r.kernel.org>, <netdev@...r.kernel.org> CC: <ast@...nel.org>, <davem@...emloft.net>, <brouer@...hat.com>, <daniel@...earbox.net>, <lorenzo.bianconi@...hat.com> Subject: Re: [PATCH bpf-next] samples/bpf: xdp_redirect_cpu: set MAX_CPUS according to NR_CPUS On 5/11/20 1:24 PM, Lorenzo Bianconi wrote: > xdp_redirect_cpu is currently failing in bpf_prog_load_xattr() > allocating cpu_map map if CONFIG_NR_CPUS is less than 64 since > cpu_map_alloc() requires max_entries to be less than NR_CPUS. > Set cpu_map max_entries according to NR_CPUS in xdp_redirect_cpu_kern.c > and get currently running cpus in xdp_redirect_cpu_user.c > > Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org> > --- > samples/bpf/xdp_redirect_cpu_kern.c | 2 +- > samples/bpf/xdp_redirect_cpu_user.c | 29 ++++++++++++++++------------- > 2 files changed, 17 insertions(+), 14 deletions(-) > > diff --git a/samples/bpf/xdp_redirect_cpu_kern.c b/samples/bpf/xdp_redirect_cpu_kern.c > index 313a8fe6d125..2baf8db1f7e7 100644 > --- a/samples/bpf/xdp_redirect_cpu_kern.c > +++ b/samples/bpf/xdp_redirect_cpu_kern.c > @@ -15,7 +15,7 @@ > #include <bpf/bpf_helpers.h> > #include "hash_func01.h" > > -#define MAX_CPUS 64 /* WARNING - sync with _user.c */ > +#define MAX_CPUS NR_CPUS > > /* Special map type that can XDP_REDIRECT frames to another CPU */ > struct { > diff --git a/samples/bpf/xdp_redirect_cpu_user.c b/samples/bpf/xdp_redirect_cpu_user.c > index 15bdf047a222..100e72cb4cf5 100644 > --- a/samples/bpf/xdp_redirect_cpu_user.c > +++ b/samples/bpf/xdp_redirect_cpu_user.c > @@ -13,6 +13,7 @@ static const char *__doc__ = > #include <unistd.h> > #include <locale.h> > #include <sys/resource.h> > +#include <sys/sysinfo.h> > #include <getopt.h> > #include <net/if.h> > #include <time.h> > @@ -24,8 +25,6 @@ static const char *__doc__ = > #include <arpa/inet.h> > #include <linux/if_link.h> > > -#define MAX_CPUS 64 /* WARNING - sync with _kern.c */ > - > /* How many xdp_progs are defined in _kern.c */ > #define MAX_PROG 6 > > @@ -40,6 +39,7 @@ static char *ifname; > static __u32 prog_id; > > static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; > +static int n_cpus; > static int cpu_map_fd; > static int rx_cnt_map_fd; > static int redirect_err_cnt_map_fd; > @@ -170,7 +170,7 @@ struct stats_record { > struct record redir_err; > struct record kthread; > struct record exception; > - struct record enq[MAX_CPUS]; > + struct record enq[]; > }; > > static bool map_collect_percpu(int fd, __u32 key, struct record *rec) > @@ -225,10 +225,11 @@ static struct datarec *alloc_record_per_cpu(void) > static struct stats_record *alloc_stats_record(void) > { > struct stats_record *rec; > - int i; > + int i, size; > > - rec = malloc(sizeof(*rec)); > - memset(rec, 0, sizeof(*rec)); > + size = sizeof(*rec) + n_cpus * sizeof(struct record); > + rec = malloc(size); > + memset(rec, 0, size); > if (!rec) { > fprintf(stderr, "Mem alloc error\n"); > exit(EXIT_FAIL_MEM); > @@ -237,7 +238,7 @@ static struct stats_record *alloc_stats_record(void) > rec->redir_err.cpu = alloc_record_per_cpu(); > rec->kthread.cpu = alloc_record_per_cpu(); > rec->exception.cpu = alloc_record_per_cpu(); > - for (i = 0; i < MAX_CPUS; i++) > + for (i = 0; i < n_cpus; i++) > rec->enq[i].cpu = alloc_record_per_cpu(); > > return rec; > @@ -247,7 +248,7 @@ static void free_stats_record(struct stats_record *r) > { > int i; > > - for (i = 0; i < MAX_CPUS; i++) > + for (i = 0; i < n_cpus; i++) > free(r->enq[i].cpu); > free(r->exception.cpu); > free(r->kthread.cpu); > @@ -350,7 +351,7 @@ static void stats_print(struct stats_record *stats_rec, > } > > /* cpumap enqueue stats */ > - for (to_cpu = 0; to_cpu < MAX_CPUS; to_cpu++) { > + for (to_cpu = 0; to_cpu < n_cpus; to_cpu++) { > char *fmt = "%-15s %3d:%-3d %'-14.0f %'-11.0f %'-10.2f %s\n"; > char *fm2 = "%-15s %3s:%-3d %'-14.0f %'-11.0f %'-10.2f %s\n"; > char *errstr = ""; > @@ -475,7 +476,7 @@ static void stats_collect(struct stats_record *rec) > map_collect_percpu(fd, 1, &rec->redir_err); > > fd = cpumap_enqueue_cnt_map_fd; > - for (i = 0; i < MAX_CPUS; i++) > + for (i = 0; i < n_cpus; i++) > map_collect_percpu(fd, i, &rec->enq[i]); > > fd = cpumap_kthread_cnt_map_fd; > @@ -549,10 +550,10 @@ static int create_cpu_entry(__u32 cpu, __u32 queue_size, > */ > static void mark_cpus_unavailable(void) > { > - __u32 invalid_cpu = MAX_CPUS; > + __u32 invalid_cpu = n_cpus; > int ret, i; > > - for (i = 0; i < MAX_CPUS; i++) { > + for (i = 0; i < n_cpus; i++) { > ret = bpf_map_update_elem(cpus_available_map_fd, &i, > &invalid_cpu, 0); > if (ret) { > @@ -688,6 +689,8 @@ int main(int argc, char **argv) > int prog_fd; > __u32 qsize; > > + n_cpus = get_nprocs(); get_nprocs() gets the number of available cpus, not including offline cpus. But gaps may exist in cpus, e.g., get_nprocs() returns 4, and cpus are 0-1,4-5. map updates will miss cpus 4-5. And in this situation, map_update will fail on offline cpus. This sample test does not need to deal with complication of cpu offlining, I think. Maybe we can get n_cpus = get_nprocs(); n_cpus_conf = get_nprocs_conf(); if (n_cpus != n_cpus_conf) { /* message that some cpus are offline and not supported. */ return error } > + > /* Notice: choosing he queue size is very important with the > * ixgbe driver, because it's driver page recycling trick is > * dependend on pages being returned quickly. The number of > @@ -757,7 +760,7 @@ int main(int argc, char **argv) > case 'c': > /* Add multiple CPUs */ > add_cpu = strtoul(optarg, NULL, 0); > - if (add_cpu >= MAX_CPUS) { > + if (add_cpu >= n_cpus) { > fprintf(stderr, > "--cpu nr too large for cpumap err(%d):%s\n", > errno, strerror(errno)); >
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