Re: skge/sk98lin slowdown with 4 Gb memory compared to 2 Gb memory
From: thunder7
Date: Sat Mar 11 2006 - 02:42:55 EST
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Fri, Mar 10, 2006 at 01:28:38PM -0800
> I suspect the optimization (in other drivers as well) that doesn't set 64 bit mask
> unless dma addresses are 64 bit. The problem would go away if you config for 64G of
> memory.
>
> This unconditionally sets 64 bit mask, does it change the situation?
>
> --- linux-2.6.orig/drivers/net/skge.c 2006-03-10 13:26:29.000000000 -0800
> +++ linux-2.6/drivers/net/skge.c 2006-03-10 13:12:38.000000000 -0800
> @@ -3265,16 +3265,10 @@
>
> pci_set_master(pdev);
>
> - if (sizeof(dma_addr_t) > sizeof(u32) &&
> - !(err = pci_set_dma_mask(pdev, DMA_64BIT_MASK))) {
> + if (!pci_set_dma_mask(pdev, DMA_64BIT_MASK) &&
> + !pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK))
> using_dac = 1;
> - err = pci_set_consistent_dma_mask(pdev, DMA_64BIT_MASK);
> - if (err < 0) {
> - printk(KERN_ERR PFX "%s unable to obtain 64 bit DMA "
> - "for consistent allocations\n", pci_name(pdev));
> - goto err_out_free_regions;
> - }
> - } else {
> + else {
> err = pci_set_dma_mask(pdev, DMA_32BIT_MASK);
> if (err) {
> printk(KERN_ERR PFX "%s no usable DMA configuration\n",
>
It makes a difference, with this patch:
INTEL :free
total used free shared buffers cached
Mem: 4043388 263432 3779956 0 23340 50576
-/+ buffers/cache: 189516 3853872
Swap: 4200888 0 4200888
INTEL :ping rusalka
PING rusalka.of.nowhere (192.168.0.3) 56(84) bytes of data.
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=2 ttl=128 time=4012 ms
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
ping: sendmsg: No buffer space available
--- rusalka.of.nowhere ping statistics ---
29 packets transmitted, 1 received, 96% packet loss, time 47037ms
rtt min/avg/max/mdev = 4012.565/4012.565/4012.565/0.000 ms, pipe 5
INTEL :
and with this patch, booting with mem=3G:
INTEL :ping rusalka
PING rusalka.of.nowhere (192.168.0.3) 56(84) bytes of data.
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=1 ttl=128 time=0.253 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=2 ttl=128 time=0.233 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=3 ttl=128 time=0.246 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=4 ttl=128 time=0.262 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=5 ttl=128 time=0.261 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=6 ttl=128 time=0.262 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=7 ttl=128 time=0.269 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=8 ttl=128 time=0.260 ms
64 bytes from rusalka.of.nowhere (192.168.0.3): icmp_seq=9 ttl=128 time=0.269 ms
--- rusalka.of.nowhere ping statistics ---
9 packets transmitted, 9 received, 0% packet loss, time 8000ms
rtt min/avg/max/mdev = 0.233/0.257/0.269/0.015 ms
INTEL :
So I don't think this patch is the solution you and I hoped for.
Sorry,
Jurriaan
--
We the unwilling, led by the unknowing have been doing the difficult
with little for so long that we are now ready to tackle the
impossible with nothing.
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Debian (Unstable) GNU/Linux 2.6.16-rc5-mm2 5503 bogomips load 0.29
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