![]() | |||||||||||||
Messages in this thread |
On Fri, 25 Jan 2002, Andrew Morton wrote: > >> > Looking at the code, I suspect that 99.9% of this "improvement" comes from > > one thing, and one thing only: you removed the "cli" in the system call > > return path.>> Before the cli was in the stock kernel, I had added it in the > low-latency patch. Careful testing showed that it added > 13 machine cycles to a system call on a P3. That sounds about right. The empty system call path is basically dominated by the trap/iret costs, and is on the order of 200 cycles or so on most CPU's. So 13 cycles would account for the roughly 5% improvement. Linus - 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/ | ||||||||||||
| Last update: 2005-03-22 12:15 [W:0.635 / U:0.240 seconds] ©2003-2008 Jasper Spaans | |||||||||||||