Jamie Lokier <[EMAIL PROTECTED]> writes:
> Richard B. Johnson wrote:
> > However, PCI to memory copying runs at about 300 megabytes per
> > second on modern PCs and memory to memory copying runs at over 1,000
> > megabytes per second. In the future, these speeds will increase.
>
> That would be
> considered to be in the "window of scarcity" (today we have 100MBit
> Ethernets and 133++MB/s PCI). Tomorrow our operating system concepts
> have to cope with 1, 10, ?? Gigabit Ethernets, Infiniband ,
> ... who knows.
We had to write our own RPC mechanism because with the standard-stacks
we had
At first, thanks for the (unexpected large) discussion and hints!
Second: sorry for the multimedia-centric viewpoint, but i think
it's an important task for future operating systems development
(or better: for a real world OS like linux) to have sophisticated
support for a _large diversity_ in
Alan Cox wrote:
> > so there's still single copy for write() of a mmap()ed page?
>
> An mmap page will go direct to disk.
Looking at the 2.4.4 code, mmap() of file followed by write() to socket
will copy the data once.
I could be mistaken (only glanced at the code quickly) but I base that
on th
On Mon, 7 May 2001, Richard B. Johnson wrote:
> Basically, "no copy" is an academic exercise. It makes the first
> packet get sent more quickly, after which everything slows to
> the natural bandwidth of the system.
>
> If you used a server for multicast-only. In other words, you
> just spewed
> so there's still single copy for write() of a mmap()ed page?
An mmap page will go direct to disk. But mmap() isnt a good model for
streaming I/O.
>
>
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Richard B. Johnson wrote:
> However, PCI to memory copying runs at about 300 megabytes per
> second on modern PCs and memory to memory copying runs at over 1,000
> megabytes per second. In the future, these speeds will increase.
That would be "big expensive modern PCs" then. Our clusters of 700M
On Mon, 7 May 2001, Richard B. Johnson wrote:
> When we get to media that can sink data as fast as we can generate
> them (it), then we have to worry about memory copy speed. However,
> these new devices are actually an IP subsystem. They generate and
> receive entire datagrams. To fully utilize
On Mon, 7 May 2001, dean gaudet wrote:
> On Mon, 7 May 2001, Richard B. Johnson wrote:
>
> > when the hardware I/O is used. This shows that the network code, alone,
> > cannot be improved very much to provide an improvement in throughput.
>
> doesn't your analysis assume that we've got nothing
> Then there's the interrupt problem, which someone will have to solve
> before they start shipping 10gigE NICs that use 1500-byte frames, 85
> interrupts/s without mitigation. Wh
In this situations polling helps rather than interrupt driven IO. When there
is heavy IO(read more interr
On Mon, May 07, 2001 at 12:12:57PM -0400, Richard B. Johnson wrote:
> you can perform network speed tests using "lo", removing the network
> board from the speed test. You will note that the network speed, due
> to software, is over 10 times faster, 30 times on some machines) than
> when the hardw
On Mon, 7 May 2001, Richard B. Johnson wrote:
> when the hardware I/O is used. This shows that the network code, alone,
> cannot be improved very much to provide an improvement in throughput.
doesn't your analysis assume that we've got nothing else interesting to do
while doing the network i/o?
On Mon, 7 May 2001, Alan Cox wrote:
> > documented so far) detailed description of the newly
> > implemented zero-copy mechanisms in the network-stack.
> > We are interested in how to use it (changed network-API?)
> > and also in the internal architecture.
>
> It is built around sendfile. Trying
On Mon, 7 May 2001, Francois Romieu wrote:
> It shows that cached code performs well with ~0us latency device/memory.
>
> Networking is about latency and pps too. They both dramatically reduce
> the (axe-)evaluated bandwith.
I think his point is more along the lines of return on investment. You
Richard B. Johnson <[EMAIL PROTECTED]> ecrit :
[...]
> when the hardware I/O is used. This shows that the network code, alone,
> cannot be improved very much to provide an improvement in throughput.
It shows that cached code performs well with ~0us latency device/memory.
Networking is about late
On Mon, 7 May 2001, Alan Cox wrote:
> > documented so far) detailed description of the newly
> > implemented zero-copy mechanisms in the network-stack.
> > We are interested in how to use it (changed network-API?)
> > and also in the internal architecture.
>
> It is built around sendfile. Tr
> documented so far) detailed description of the newly
> implemented zero-copy mechanisms in the network-stack.
> We are interested in how to use it (changed network-API?)
> and also in the internal architecture.
It is built around sendfile. Trying to do zero copy on pages with user space
map
Hi all,
we are currently developing (as part of my dissertation)
a research-platform to study some new ideas in
constructing transport systems to support applications
with realtime-requirements (e.g. multimedia) and new
networking technologies. The test-platform consists of
typical multimedia
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