Re: close() slow on socketpairs?

[David S. Miller]

Please try this 2.2.x patch.  It fixes the 2.2.x performance
problem with your example code for me.

--- ./include/net/af_unix.h.~1~ Fri Apr 11 21:30:23 1997
+++ ./include/net/af_unix.h     Tue Oct 17 00:04:32 2000
@@ -7,7 +7,7 @@
 typedef struct sock unix_socket;
 extern void unix_gc(void);
 
-#define UNIX_HASH_SIZE 16
+#define UNIX_HASH_SIZE 256
 
 extern unix_socket *unix_socket_table[UNIX_HASH_SIZE+1];
 
--- ./net/unix/af_unix.c.~1~    Fri May 26 21:46:44 2000
+++ ./net/unix/af_unix.c        Tue Oct 17 01:49:47 2000
@@ -110,6 +110,8 @@
 
 #define min(a,b)       (((a)<(b))?(a):(b))
 
+extern int unix_tot_inflight;
+
 int sysctl_unix_delete_delay = HZ;
 int sysctl_unix_destroy_delay = 10*HZ;
 int sysctl_unix_max_dgram_qlen = 10;
@@ -130,7 +132,6 @@
 {
        hash ^= hash>>16;
        hash ^= hash>>8;
-       hash ^= hash>>4;
        return hash;
 }
 
@@ -240,7 +241,7 @@
 {
        unix_socket *s;
 
-       for (s=unix_socket_table[(hash^type)&0xF]; s; s=s->next)
+       for (s=unix_socket_table[(hash^type)&(UNIX_HASH_SIZE-1)]; s; s=s->next)
        {
                if(s->protinfo.af_unix.addr->len==len &&
                   memcmp(s->protinfo.af_unix.addr->name, sunname, len) == 0 &&
@@ -257,7 +258,7 @@
 {
        unix_socket *s;
 
-       for (s=unix_socket_table[i->i_ino & 0xF]; s; s=s->next)
+       for (s=unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]; s; s=s->next)
        {
                struct dentry *dentry = s->protinfo.af_unix.dentry;
 
@@ -344,7 +345,8 @@
         *        What the above comment does talk about? --ANK(980817)
         */
 
-       unix_gc();              /* Garbage collect fds */       
+       if (unix_tot_inflight)
+               unix_gc();              /* Garbage collect fds */       
        return 0;
 }
        
@@ -519,7 +521,7 @@
 
        sk->protinfo.af_unix.addr = addr;
        unix_remove_socket(sk);
-       sk->protinfo.af_unix.list = &unix_socket_table[(addr->hash ^ sk->type)&0xF];
+       sk->protinfo.af_unix.list = &unix_socket_table[(addr->hash ^ 
+sk->type)&(UNIX_HASH_SIZE - 1)];
        unix_insert_socket(sk);
        return 0;
 }
@@ -607,7 +609,7 @@
                }
                unix_remove_socket(sk);
                sk->protinfo.af_unix.addr = addr;
-               sk->protinfo.af_unix.list = &unix_socket_table[(hash^sk->type)&0xF];
+               sk->protinfo.af_unix.list = 
+&unix_socket_table[(hash^sk->type)&(UNIX_HASH_SIZE - 1)];
                unix_insert_socket(sk);
                return 0;
        }
@@ -628,7 +630,7 @@
                        return err;
        }
        unix_remove_socket(sk);
-       sk->protinfo.af_unix.list = &unix_socket_table[dentry->d_inode->i_ino & 0xF];
+       sk->protinfo.af_unix.list = &unix_socket_table[dentry->d_inode->i_ino & 
+(UNIX_HASH_SIZE - 1)];
        sk->protinfo.af_unix.dentry = dentry;
        unix_insert_socket(sk);
 
--- ./net/unix/garbage.c.~1~    Tue Mar 23 17:03:06 1999
+++ ./net/unix/garbage.c        Tue Oct 17 01:49:11 2000
@@ -108,6 +108,8 @@
        return u_sock;
 }
 
+int unix_tot_inflight;
+
 /*
  *     Keep the number of times in flight count for the file
  *     descriptor if it is for an AF_UNIX socket.
@@ -116,15 +118,19 @@
 void unix_inflight(struct file *fp)
 {
        unix_socket *s=unix_get_socket(fp);
-       if(s)
+       if (s) {
                s->protinfo.af_unix.inflight++;
+               unix_tot_inflight++;
+       }
 }
 
 void unix_notinflight(struct file *fp)
 {
        unix_socket *s=unix_get_socket(fp);
-       if(s)
+       if (s) {
                s->protinfo.af_unix.inflight--;
+               unix_tot_inflight--;
+       }
 }
 
 
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