[lkml]   [2001]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Is sendfile all that sexy?

On Sun, 14 Jan 2001, jamal wrote:

> regular ttcp, no ZC and no sendfile. [...]
> Throughput: ~99MB/sec (for those obsessed with Mbps ~810Mbps)
> CPU abuse: server side 87% client side 22% [...]

> sendfile server.
> - throughput: 86MB/sec
> - CPU: server 100%, client 17%

i believe what you are seeing here is the overhead of the pagecache. When
using sendmsg() only, you do not read() the file every time, right? Is
ttcp using multiple threads? In that case if the sendfile() is using the
*same* file all the time, creating SMP locking overhead.

if this is the case, what result do you get if you use a separate,
isolated file per process? (And i bet that with DaveM's pagecache
scalability patch the situation would also get much better - the global
pagecache_lock hurts.)


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:28    [W:0.390 / U:1.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site