Andrew Morton wrote:
On Fri, 22 Sep 2006 07:27:18 +0000 (GMT)
Holger Kiehl <[EMAIL PROTECTED]> wrote:

I get some of the "page allocation failure" errors. My hardware is 4 CPU
Opteron with one quad + one dual intel e1000 cards. Kernel is plain 2.6.18
and for two cards MTU is set to 9000.

    Sep 21 21:03:15 athena kernel: vsftpd: page allocation failure. order:3, 
mode:0x20
    Sep 21 21:03:15 athena kernel:
    Sep 21 21:03:15 athena kernel: Call Trace:
    Sep 21 21:03:15 athena kernel:  <IRQ> [<ffffffff8024e516>] 
__alloc_pages+0x282/0x29b
    Sep 21 21:03:15 athena kernel:  [<ffffffff8807aa93>] 
:ip_tables:ipt_do_table+0x1eb/0x318
    Sep 21 21:03:15 athena kernel:  [<ffffffff8026614b>] cache_grow+0x134/0x33d
    Sep 21 21:03:15 athena kernel:  [<ffffffff8026664c>] 
cache_alloc_refill+0x189/0x1d7
    Sep 21 21:03:15 athena kernel:  [<ffffffff80266724>] __kmalloc+0x8a/0x94
    Sep 21 21:03:15 athena kernel:  [<ffffffff803b5438>] __alloc_skb+0x5c/0x123
    Sep 21 21:03:15 athena kernel:  [<ffffffff803b5f2e>] 
__netdev_alloc_skb+0x12/0x2d
    Sep 21 21:03:15 athena kernel:  [<ffffffff8033cb22>] 
e1000_alloc_rx_buffers+0x6f/0x2f3
    Sep 21 21:03:15 athena kernel:  [<ffffffff803d1234>] 
ip_local_deliver+0x173/0x23b
    Sep 21 21:03:15 athena kernel:  [<ffffffff8033d29a>] 
e1000_clean_rx_irq+0x4f4/0x514

Is OK, it's just a warning and it is expected - the kernel will recover.

I'm half-inclined to shut the warning up by sticking a __GFP_NOWARN in there.

But on the other hand, that warning is handy sometimes.  How come kmalloc
decided to request a 32k hunk of memory when the MTU size is only 9k?  Is
the driver doing something dumb?

        else if (max_frame <= E1000_RXBUFFER_8192)
                adapter->rx_buffer_len = E1000_RXBUFFER_8192;
        else if (max_frame <= E1000_RXBUFFER_16384)
                adapter->rx_buffer_len = E1000_RXBUFFER_16384;

It sure is.

This is going to cause an 9000-byte MTU to use a 16384-byte allocation. e1000_alloc_rx_buffers() adds two bytes to that, so we do kmalloc(16386),
which causes the slab allocator to request 32768 bytes.  All for a 9kbyte skb.

I wonder if we can't account for NET_IP_ALIGN when selecting bufsize, to get at rid of at least 1 order size before we netdev_alloc_skb. This should make 9k frames only kmalloc(16384) and thus stay within the 16k boundary. I hope.

Completely untested: don't commit :)

Auke

---

e1000: account for NET_IP_ALIGN when calculating bufsiz

Account for NET_IP_ALIGN when requesting buffer sizes from netdev_alloc_skb to reduce slab allocation by half.

Signed-off-by: Auke Kok <[EMAIL PROTECTED]>

diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index bb0d129..20b1f39 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -1144,7 +1144,7 @@ #endif

        pci_read_config_word(pdev, PCI_COMMAND, &hw->pci_cmd_word);

-       adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
+       adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE + NET_IP_ALIGN;
        adapter->rx_ps_bsize0 = E1000_RXBUFFER_128;
        hw->max_frame_size = netdev->mtu +
                             ENET_HEADER_SIZE + ETHERNET_FCS_SIZE;
@@ -3234,26 +3234,27 @@ #define MAX_STD_JUMBO_FRAME_SIZE 9234
         * larger slab size
         * i.e. RXBUFFER_2048 --> size-4096 slab */

-       if (max_frame <= E1000_RXBUFFER_256)
+       if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_256)
                adapter->rx_buffer_len = E1000_RXBUFFER_256;
-       else if (max_frame <= E1000_RXBUFFER_512)
+       else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_512)
                adapter->rx_buffer_len = E1000_RXBUFFER_512;
-       else if (max_frame <= E1000_RXBUFFER_1024)
+       else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_1024)
                adapter->rx_buffer_len = E1000_RXBUFFER_1024;
-       else if (max_frame <= E1000_RXBUFFER_2048)
+       else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_2048)
                adapter->rx_buffer_len = E1000_RXBUFFER_2048;
-       else if (max_frame <= E1000_RXBUFFER_4096)
+       else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_4096)
                adapter->rx_buffer_len = E1000_RXBUFFER_4096;
-       else if (max_frame <= E1000_RXBUFFER_8192)
+       else if (max_frame + NET_IP_ALIGN <= E1000_RXBUFFER_8192)
                adapter->rx_buffer_len = E1000_RXBUFFER_8192;
-       else if (max_frame <= E1000_RXBUFFER_16384)
+       else
                adapter->rx_buffer_len = E1000_RXBUFFER_16384;

        /* adjust allocation if LPE protects us, and we aren't using SBP */
        if (!adapter->hw.tbi_compatibility_on &&
            ((max_frame == MAXIMUM_ETHERNET_FRAME_SIZE) ||
             (max_frame == MAXIMUM_ETHERNET_VLAN_SIZE)))
-               adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE;
+               adapter->rx_buffer_len = MAXIMUM_ETHERNET_VLAN_SIZE
+                                        + NET_IP_ALIGN;

        netdev->mtu = new_mtu;

@@ -4076,7 +4076,8 @@ e1000_alloc_rx_buffers(struct e1000_adap
        struct e1000_buffer *buffer_info;
        struct sk_buff *skb;
        unsigned int i;
-       unsigned int bufsz = adapter->rx_buffer_len + NET_IP_ALIGN;
+       /* we have already accounted for NET_IP_ALIGN */
+       unsigned int bufsz = adapter->rx_buffer_len;

        i = rx_ring->next_to_use;
        buffer_info = &rx_ring->buffer_info[i];
-
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