Messages in this thread Patch in this message | | | Date | Mon, 23 Dec 2002 19:08:48 +0530 | From | Ravikiran G Thirumalai <> | Subject | [patch] Convert sockets_in_use to use per_cpu areas |
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Hi, Here's a simple patch to change sockets_in_use to make use of per-cpu areas.
I have couple of questions though... 1. Was this var made per-cpu just to avoid atomic_t or locking or are there real life workloads which cause too many sock_alloc and sock_releases to cause cacheline bouncing? 2. Is this var required? since we can just sum up all proto->stats.inuse and remove this var altogether? (This var is read only for /proc reporting)
Thanks, Kiran
diff -ruN -X dontdiff linux-2.5.52/net/socket.c sockets_in_use-2.5.52/net/socket.c --- linux-2.5.52/net/socket.c Mon Dec 16 07:37:53 2002 +++ sockets_in_use-2.5.52/net/socket.c Mon Dec 23 11:48:44 2002 @@ -189,10 +189,7 @@ * Statistics counters of the socket lists */ -static union { - int counter; - char __pad[SMP_CACHE_BYTES]; -} sockets_in_use[NR_CPUS] __cacheline_aligned = {{0}}; +static DEFINE_PER_CPU(int, sockets_in_use); /* * Support routines. Move socket addresses back and forth across the kernel/user @@ -475,7 +472,8 @@ inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; - sockets_in_use[smp_processor_id()].counter++; + get_cpu_var(sockets_in_use)++; + put_cpu_var(sockets_in_use); return sock; } @@ -511,7 +509,8 @@ if (sock->fasync_list) printk(KERN_ERR "sock_release: fasync list not empty!\n"); - sockets_in_use[smp_processor_id()].counter--; + get_cpu_var(sockets_in_use)--; + put_cpu_var(sockets_in_use); if (!sock->file) { iput(SOCK_INODE(sock)); return; @@ -1851,7 +1850,7 @@ int counter = 0; for (cpu = 0; cpu < NR_CPUS; cpu++) - counter += sockets_in_use[cpu].counter; + counter += per_cpu(sockets_in_use, cpu); /* It can be negative, by the way. 8) */ if (counter < 0) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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