Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752329Ab0AJS00 (ORCPT ); Sun, 10 Jan 2010 13:26:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751660Ab0AJS0Z (ORCPT ); Sun, 10 Jan 2010 13:26:25 -0500 Received: from khc.piap.pl ([195.187.100.11]:35644 "EHLO khc.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751482Ab0AJS0Z (ORCPT ); Sun, 10 Jan 2010 13:26:25 -0500 From: Krzysztof Halasa To: "Paul G. Allen" Cc: linux-kernel Subject: Re: Linux Serial Performance References: Date: Sun, 10 Jan 2010 19:26:22 +0100 In-Reply-To: (Paul G. Allen's message of "Sat, 9 Jan 2010 10:57:48 -0800") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1526 Lines: 34 "Paul G. Allen" writes: > I ran some tests on Windows XP and Linux CentOS 5.1 using the Sun > NetBeans IDE 6.7.1 profiler. The same Java code on both Linux and XP > machines, the same model of machine (Dell, Pentium 4 3GHz, 2.5GB > memory). I am using the Sun comm API currently, and previously I was > using the Serlio API. In all cases, the profiler shows the serial Tx > to be about 20x faster (twenty times) on Windows XP than in Linux. It > takes Linux several seconds to Tx 1024 byte blocks of data over the > serial port where Windows XP takes a fraction of a second. I don't know about Java, but I'm using 460 kb/s and 920 kb/s serial ports and Linux can transmit (and receive) full speed data without any problem. This includes mobile Pentium III 500 MHz with 460 kb/s NS super IO chip. 4-port OX16PCI954, PL2303 (max 2) and FTDI2232-based USB dongles also work as well. I know people use ca. 4 Mb/s async serial (with PPP). The last time I remember serial IO problems it was 8-port 8251-based ISA card on 486DX. I think it was reliable at max 19200 b/s. Perhaps you're requesting hardware (or software) handshaking when it's unavailable? Or maybe there is some "padding" configured? I wonder what does strace say about it. -- Krzysztof Halasa -- 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/