linux-kernel - [PATCH 1/2] perf record: Support s390 random socket

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Date:   Mon, 11 Jun 2018 09:31:52 +0200
From:   Thomas Richter <tmricht@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, Thomas Richter <tmricht@...ux.ibm.com>
Subject: [PATCH 1/2] perf record: Support s390 random socket_id assignment

On s390 the socket identifier assigned to a CPU identifier is
random and (depending on the configuration of the LPAR) may be higher
than the CPU identifier. This is currently not supported.

Fix this by allowing arbitrary socket identifiers being assigned to
CPU id.

Output before:

[root@...lp27 perf]# ./perf report --header -I -v
 ...
 socket_id number is too big.You may need to upgrade the perf tool.
 Error:
 The perf.data file has no samples!
 # ========
 # captured on    : Tue May 29 09:29:57 2018
 # header version : 1
 ...
 # Core ID and Socket ID information is not available
 ...
[root@...lp27 perf]#

Output after:
[root@...lp27 perf]# ./perf report --header -I -v
 ...
 Error:
 The perf.data file has no samples!
 # ========
 # captured on    : Tue May 29 09:29:57 2018
 # header version : 1
 ...
 # CPU 0: Core ID 0, Socket ID 6
 # CPU 1: Core ID 1, Socket ID 3
 # CPU 2: Core ID -1, Socket ID -1
 ...
[root@...lp27 perf]#

Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@...ux.ibm.com>
---
 tools/perf/util/header.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index a8bff2178fbc..34e9d6b9d945 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2113,6 +2113,7 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
 	int cpu_nr = ff->ph->env.nr_cpus_avail;
 	u64 size = 0;
 	struct perf_header *ph = ff->ph;
+	bool do_core_id_test = true;
 
 	ph->env.cpu = calloc(cpu_nr, sizeof(*ph->env.cpu));
 	if (!ph->env.cpu)
@@ -2167,6 +2168,13 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
 		return 0;
 	}
 
+	/* On s390 the socket_id number is not related to the numbers of cpus.
+	 * The socket_id number might be higher than the numbers of cpus.
+	 * This depends on the configuration.
+	 */
+	if (ph->env.arch && !strncmp(ph->env.arch, "s390", 4))
+		do_core_id_test = false;
+
 	for (i = 0; i < (u32)cpu_nr; i++) {
 		if (do_read_u32(ff, &nr))
 			goto free_cpu;
@@ -2176,7 +2184,7 @@ static int process_cpu_topology(struct feat_fd *ff, void *data __maybe_unused)
 		if (do_read_u32(ff, &nr))
 			goto free_cpu;
 
-		if (nr != (u32)-1 && nr > (u32)cpu_nr) {
+		if (do_core_id_test && nr != (u32)-1 && nr > (u32)cpu_nr) {
 			pr_debug("socket_id number is too big."
 				 "You may need to upgrade the perf tool.\n");
 			goto free_cpu;
-- 
2.14.3