From 406dae88df5ce989f9166929522e7ec5c5899fce Mon Sep 17 00:00:00 2001
From: nocjj <1250062498@qq.com>
Date: Fri, 12 Mar 2021 14:30:26 +0800
Subject: [PATCH] vcpu_list: pre malloc vcpu list to improve performance

It costs a lot of time to malloc and memset vcpu_list while getting a new vcpu.
And vcpu num is limited to MAX_VCPU_NUM = 1024, so pre malloc MAX_VCPU_NUM mem,
which will improve vmtop cpu usage a lot.

Signed-off-by: nocjj <1250062498@qq.com>
---
 src/vcpu_stat.c | 5 +++--
 src/vmtop.c     | 1 +
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/vcpu_stat.c b/src/vcpu_stat.c
index 222e4d2..1578ec4 100644
--- a/src/vcpu_stat.c
+++ b/src/vcpu_stat.c
@@ -97,7 +97,7 @@ int get_vcpu_list(struct domain_list *list)
     if (!fp) {
         return -1;
     }
-    clear_domains(list);
+    list->num = 0;
     while (fgets(buf, BUF_SIZE - 1, fp)) {
         char *p = NULL;
         char *p_next = NULL;
@@ -107,7 +107,7 @@ int get_vcpu_list(struct domain_list *list)
         if (list->num >= MAX_VCPU_NUM) {
             break;
         }
-        struct domain *dom = add_domains(list);
+        struct domain *dom = &(list->domains[list->num]);
         for (p = strtok_r(buf, " \t\r\n", &p_next); p && i < vcpu_stat_size;
              p = strtok_r(NULL, " \t\r\n", &p_next)) {
             if (vcpu_stat_stab[i].get_fun) {
@@ -116,6 +116,7 @@ int get_vcpu_list(struct domain_list *list)
             }
             i++;
         }
+        list->num++;
     }
     fclose(fp);
     return list->num;
diff --git a/src/vmtop.c b/src/vmtop.c
index f5fd4bd..9e273c6 100644
--- a/src/vmtop.c
+++ b/src/vmtop.c
@@ -55,6 +55,7 @@ static void init_parameter(void)
     init_domains(&scr_cur);
     init_domains(&scr_pre);
     init_domains(&vcpu_list);
+    vcpu_list.domains = malloc(sizeof(struct domain) * MAX_VCPU_NUM);
     begin_task = 1;
     begin_field = 1;
     thread_mode = 0;    /* default not to show threads */
-- 
2.27.0