From 3eb6cbec50a5cbe4c3465d60ba6aea7bf2845cd1 Mon Sep 17 00:00:00 2001
From: Damjan Marion <damarion@cisco.com>
Date: Mon, 12 Feb 2024 19:44:58 +0000
Subject: vppinfra: os agnostic api for getting CPU information

Avoid direct sysfs reads when possible...

Type: improvement
Change-Id: I2b84cd18f3da47925d068951f24b79b5b6e20bb1
Signed-off-by: Damjan Marion <damarion@cisco.com>
---
 src/vlib/buffer.c          |  6 +-----
 src/vlib/physmem.c         |  1 -
 src/vlib/threads.c         | 24 +++++++----------------
 src/vppinfra/linux/mem.c   |  1 -
 src/vppinfra/linux/sysfs.c | 14 +++++++++++---
 src/vppinfra/linux/sysfs.h |  3 ++-
 src/vppinfra/pmalloc.c     |  2 ++
 src/vppinfra/unix-misc.c   | 47 ++++++++++++++++++++++++++++++++++++++++++++--
 src/vppinfra/unix.h        |  9 +++++++++
 9 files changed, 77 insertions(+), 30 deletions(-)

diff --git a/src/vlib/buffer.c b/src/vlib/buffer.c
index b43c1dace97..674f15d5dc6 100644
--- a/src/vlib/buffer.c
+++ b/src/vlib/buffer.c
@@ -43,7 +43,6 @@
  * Allocate/free network buffers.
  */
 
-#include <vppinfra/linux/sysfs.h>
 #include <vppinfra/bitmap.h>
 #include <vppinfra/unix.h>
 #include <vlib/vlib.h>
@@ -837,10 +836,7 @@ vlib_buffer_main_init (struct vlib_main_t * vm)
   clib_spinlock_init (&bm->buffer_known_hash_lockp);
 
   bmp = os_get_online_cpu_node_bitmap ();
-
-  if ((err = clib_sysfs_read ("/sys/devices/system/node/has_memory", "%U",
-			      unformat_bitmap_list, &bmp_has_memory)))
-    clib_error_free (err);
+  bmp_has_memory = os_get_cpu_with_memory_bitmap ();
 
   if (bmp && bmp_has_memory)
     bmp = clib_bitmap_and (bmp, bmp_has_memory);
diff --git a/src/vlib/physmem.c b/src/vlib/physmem.c
index c6727bb92cb..84c61d2a44f 100644
--- a/src/vlib/physmem.c
+++ b/src/vlib/physmem.c
@@ -22,7 +22,6 @@
 #include <unistd.h>
 
 #include <vppinfra/clib.h>
-#include <vppinfra/linux/sysfs.h>
 #include <vlib/vlib.h>
 #include <vlib/physmem.h>
 #include <vlib/unix/unix.h>
diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index f0cb69b3400..713e1927d1f 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -19,7 +19,6 @@
 #include <vppinfra/format.h>
 #include <vppinfra/time_range.h>
 #include <vppinfra/interrupt.h>
-#include <vppinfra/linux/sysfs.h>
 #include <vppinfra/bitmap.h>
 #include <vppinfra/unix.h>
 #include <vlib/vlib.h>
@@ -427,30 +426,21 @@ vlib_worker_thread_bootstrap_fn (void *arg)
 void
 vlib_get_thread_core_numa (vlib_worker_thread_t * w, unsigned cpu_id)
 {
-  const char *sys_cpu_path = "/sys/devices/system/cpu/cpu";
-  const char *sys_node_path = "/sys/devices/system/node/node";
   clib_bitmap_t *nbmp = 0, *cbmp = 0;
-  u32 node;
-  u8 *p = 0;
-  int core_id = -1, numa_id = -1;
-
-  p = format (p, "%s%u/topology/core_id%c", sys_cpu_path, cpu_id, 0);
-  clib_sysfs_read ((char *) p, "%d", &core_id);
-  vec_reset_length (p);
+  int node, core_id = -1, numa_id = -1;
 
+  core_id = os_get_cpu_phys_core_id (cpu_id);
   nbmp = os_get_online_cpu_node_bitmap ();
+
   clib_bitmap_foreach (node, nbmp)  {
-    p = format (p, "%s%u/cpulist%c", sys_node_path, node, 0);
-    clib_sysfs_read ((char *) p, "%U", unformat_bitmap_list, &cbmp);
-    if (clib_bitmap_get (cbmp, cpu_id))
-      numa_id = node;
-    vec_reset_length (cbmp);
-    vec_reset_length (p);
+      cbmp = os_get_cpu_on_node_bitmap (node);
+      if (clib_bitmap_get (cbmp, cpu_id))
+	numa_id = node;
+      vec_reset_length (cbmp);
   }
 
   vec_free (nbmp);
   vec_free (cbmp);
-  vec_free (p);
 
   w->core_id = core_id;
   w->numa_id = numa_id;
diff --git a/src/vppinfra/linux/mem.c b/src/vppinfra/linux/mem.c
index 8f696a1036a..734f5c4788c 100644
--- a/src/vppinfra/linux/mem.c
+++ b/src/vppinfra/linux/mem.c
@@ -31,7 +31,6 @@
 #include <vppinfra/bitmap.h>
 #include <vppinfra/format.h>
 #include <vppinfra/clib_error.h>
-#include <vppinfra/linux/sysfs.h>
 
 #ifndef F_LINUX_SPECIFIC_BASE
 #define F_LINUX_SPECIFIC_BASE 1024
diff --git a/src/vppinfra/linux/sysfs.c b/src/vppinfra/linux/sysfs.c
index 6d9f859640c..61ee6378c8c 100644
--- a/src/vppinfra/linux/sysfs.c
+++ b/src/vppinfra/linux/sysfs.c
@@ -237,13 +237,21 @@ clib_sysfs_prealloc_hugepages (int numa_node, int log2_page_size, int nr)
   return clib_sysfs_set_nr_hugepages (numa_node, log2_page_size, n + needed);
 }
 
-__clib_export uword *
-clib_sysfs_list_to_bitmap (char *filename)
+__clib_export clib_bitmap_t *
+clib_sysfs_read_bitmap (char *fmt, ...)
 {
   FILE *fp;
   uword *r = 0;
+  va_list va;
+  u8 *filename;
+
+  va_start (va, fmt);
+  filename = va_format (0, fmt, &va);
+  va_end (va);
+  vec_add1 (filename, 0);
 
-  fp = fopen (filename, "r");
+  fp = fopen ((char *) filename, "r");
+  vec_free (filename);
 
   if (fp != NULL)
     {
diff --git a/src/vppinfra/linux/sysfs.h b/src/vppinfra/linux/sysfs.h
index a616fa422a1..f2f822d9741 100644
--- a/src/vppinfra/linux/sysfs.h
+++ b/src/vppinfra/linux/sysfs.h
@@ -17,6 +17,7 @@
 #define included_linux_sysfs_h
 
 #include <vppinfra/error.h>
+#include <vppinfra/bitmap.h>
 
 clib_error_t *clib_sysfs_write (char *file_name, char *fmt, ...);
 
@@ -33,7 +34,7 @@ clib_error_t *clib_sysfs_get_surplus_hugepages (int numa_node,
 clib_error_t *clib_sysfs_prealloc_hugepages (int numa_node,
 					     int log2_page_size, int nr);
 
-uword *clib_sysfs_list_to_bitmap (char *filename);
+uword *clib_sysfs_read_bitmap (char *fmt, ...);
 
 #endif /* included_linux_sysfs_h */
 
diff --git a/src/vppinfra/pmalloc.c b/src/vppinfra/pmalloc.c
index ff392a1bf22..2a27379b573 100644
--- a/src/vppinfra/pmalloc.c
+++ b/src/vppinfra/pmalloc.c
@@ -22,7 +22,9 @@
 #include <sched.h>
 
 #include <vppinfra/format.h>
+#ifdef __linux__
 #include <vppinfra/linux/sysfs.h>
+#endif
 #include <vppinfra/mem.h>
 #include <vppinfra/hash.h>
 #include <vppinfra/pmalloc.h>
diff --git a/src/vppinfra/unix-misc.c b/src/vppinfra/unix-misc.c
index 623b2e98555..e0591ff4604 100644
--- a/src/vppinfra/unix-misc.c
+++ b/src/vppinfra/unix-misc.c
@@ -268,7 +268,7 @@ __clib_export clib_bitmap_t *
 os_get_online_cpu_core_bitmap ()
 {
 #if __linux__
-  return clib_sysfs_list_to_bitmap ("/sys/devices/system/cpu/online");
+  return clib_sysfs_read_bitmap ("/sys/devices/system/cpu/online");
 #else
   return 0;
 #endif
@@ -278,11 +278,54 @@ __clib_export clib_bitmap_t *
 os_get_online_cpu_node_bitmap ()
 {
 #if __linux__
-  return clib_sysfs_list_to_bitmap ("/sys/devices/system/node/online");
+  return clib_sysfs_read_bitmap ("/sys/devices/system/node/online");
 #else
   return 0;
 #endif
 }
+__clib_export clib_bitmap_t *
+os_get_cpu_on_node_bitmap (int node)
+{
+#if __linux__
+  return clib_sysfs_read_bitmap ("/sys/devices/system/node/node%u/cpulist",
+				 node);
+#else
+  return 0;
+#endif
+}
+
+__clib_export clib_bitmap_t *
+os_get_cpu_with_memory_bitmap ()
+{
+#if __linux__
+  return clib_sysfs_read_bitmap ("/sys/devices/system/node/has_memory");
+#else
+  return 0;
+#endif
+}
+
+__clib_export int
+os_get_cpu_phys_core_id (int cpu_id)
+{
+#if __linux
+  int core_id = -1;
+  clib_error_t *err;
+  u8 *p;
+
+  p =
+    format (0, "/sys/devices/system/cpu/cpu%u/topology/core_id%c", cpu_id, 0);
+  err = clib_sysfs_read ((char *) p, "%d", &core_id);
+  vec_free (p);
+  if (err)
+    {
+      clib_error_free (err);
+      return -1;
+    }
+  return core_id;
+#else
+  return -1;
+#endif
+}
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/vppinfra/unix.h b/src/vppinfra/unix.h
index b43043a567b..651f9bb99e0 100644
--- a/src/vppinfra/unix.h
+++ b/src/vppinfra/unix.h
@@ -59,6 +59,15 @@ clib_bitmap_t *os_get_online_cpu_core_bitmap ();
 /* Retrieve bitmap of online cpu nodes (sockets) */
 clib_bitmap_t *os_get_online_cpu_node_bitmap ();
 
+/* Retrieve bitmap of cpus with memory */
+clib_bitmap_t *os_get_cpu_with_memory_bitmap ();
+
+/* Retrieve bitmap of cpus on specific node */
+clib_bitmap_t *os_get_cpu_on_node_bitmap (int node);
+
+/* Retrieve physical core id of specific cpu, -1 if not available */
+int os_get_cpu_phys_core_id (int cpu);
+
 #endif /* included_clib_unix_h */
 
 /*
-- 
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