z/VSE Fast Path to Linux on System z

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Learn about z/VSE Fast Path to Linux on System z.For more information, visit http://ibm.co/PNo9C

Text of z/VSE Fast Path to Linux on System z

  • 1. IBM System z Live Virtual Classz/VSE Fast Path to Linux on System zIngo Franzki, IBM 2011 IBM Corporation
  • 2. IBM System z Live Virtual Class z/VSE Applications communicating with Applications on Linux z/VSE Linux on System z VSE Conn Data VTAPE Server Java WebSphere Application App Server Application Application Application VSE Conn WebSphere VSAM Client Data DB2 Client MQ Redirector VTAPE SOAP Server CICS Application CICS Web VSAM Redir DB2 Client MQ Server DB2 Server Support & SOAP Server TCP/IP Stack TCP/IP Stack Supervisor Kernel OSA OSA Express, HiperSockets, VSWITCH OSA LPARs or z/VM2 2011 IBM Corporation
  • 3. IBM System z Live Virtual Classz/VSE Applications communicating with Applications on Linux Communication is mostly based on TCP/IP Although z/VSE and Linux run on the same box TCP/IP Allow reliable communication over a non-reliable network Uses sequence numbers, acknowledges, checksums To protect against packet loss, duplicate packets, packet sequence errors, damaged or incomplete packets, etc. Time consuming processing When z/VSE and Linux run side by side on the same box Why do we need all this expensive processing in this case? There should be a more direct communication method ! z/VSE Fast Path to Linux on System z (for short: Linux Fast Path or just LFP)3 2011 IBM Corporation
  • 4. IBM System z Live Virtual ClassFast Path to Linux on System z (LFP) Allows selected TCP/IP applications to communicate with the TCP/IP stack on Linux Application Application without using a TCP/IP stack on z/VSE LFP Daemon The Linux Fast Path uses an IUCV connection between z/VSE and Linux on System z TCP/IP Stack Both systems run in the same z/VM-mode LPAR on IBM z10, z196 or z114 servers z/VSE Supervisor Kernel All socket requests are transparently forwarded to a Linux on System z system running in the same z/VM IUCV z/VM 6.1 5.4 On Linux on System z, the LFP daemon must run z/VM-Mode LPAR This daemon fulfills all socket requests by forwarding them to the Linux TCP/IP stack The Fast Path to Linux on System z provides standard TCP/IP socket APIs for programs running on z/VSE Possible performance increase due to: Less overhead for TCP/IP processing on z/VSE (TCP, sequence numbers and acknowledging, checksums, resends, etc) More reliable communication method (IUCV) compared to HiperSockets, which is a network device, with all its packet drops, resends, etc.4 2011 IBM Corporation
  • 5. IBM System z Live Virtual ClassCommunication using TCP/IP 1. Data is passed from the application to the TCP/IP stack partition (using cross-partition communication mechanisms, involves dispatching). 2. TCP/IP builds IP packets (including TCP, checksums, sequence numbers, etc) and sends it through the OSAX device driver. 3. The TCP/IP stack passes the packets to the network device driver for use with HiperSockets 4. The HiperSockets network forwards the packets to the Linux image. 5. The Linux HiperSockets device driver receives the packets and passes them to the TCP/IP stack. The TCP/IP stack on Linux checks and unpacks the IP and TCP header. This processing includes handling for retransmissions, sequence numbers and acknowledging, validating checksums and so on. 6. The TCP/IP stack passes the data to the application which processes it.5 2011 IBM Corporation
  • 6. IBM System z Live Virtual ClassCommunication using Linux Fast Path 1. The data to be sent is passed to the Linux Fast Path (LFP) stack running on z/VSE. 2. The LFP stack builds IUCV packets including the data, and sends the packets via the IUCV channel to the Linux image. 3. The Linux IUCV device driver receives the packets and passes them to the LFP Daemon running on the Linux image. The LFP Daemon then processes the data received from the IUCV channel, and translates it into a socket call. 4. The socket call is processed by the TCP/IP stack. Because the data is to be sent to an application that runs on the same Linux system, the TCP/IP stack simply forwards the data directly to the application (using a Unix pipe, thus no TCP/IP processing required). 5. The application receives the data and processes it.6 2011 IBM Corporation
  • 7. IBM System z Live Virtual ClassPerformance measurements using Linux Fast PathComparison TCP/IP for VSE versus Linux Fast Path: Workload TCP/IP for VSE Linux Fast Path (LFP) Difference FTP (BSI FTP server) VSE Linux (1GB) 19 MB/sec 72 MB/sec 3.7 times faster (NULL file, no I/O) 29% CPU (5% App + 24% TCPIP) 20% CPU (App) 9% less CPU Linux VSE (1GB) 21 MB/sec 70 MB/sec 3.3 times faster (NULL file, no I/O) 55% CPU (11% App + 44% TCPIP) 20% CPU (App) 35% less CPU Socket Application (running 3 times) VSE Linux (100MB) 4.6 MB/sec (*3 = 13.8 MB/sec) 14.6 MB/sec (*3 = 43.8 MB/sec) 3.2 times faster Linux VSE (100MB) 9.7 MB/sec (*3 = 29.1 MB/sec) 16.2 MB/sec (*3 = 48.6 MB/sec) 1,7 times faster 26% CPU (3*1% App + 23% TCP/IP) 9 % CPU (3*3% App) 17% less CPU Environment: IBM System z10 EC (2097-722). TCP/IP connection via shared OSA adapter. Significant benefits in transfer rate as well as CPU usage7 2011 IBM Corporation
  • 8. IBM System z Live Virtual ClassPrerequisites for using the Linux Fast Path If you use a z/VM-mode LPAR, z/VM 5.4 or later. Otherwise, any z/VM release that is supported by z/VSE If you use a z/VM-mode LPAR, IBM System z10, z196 or z114. Otherwise, any server supported by z/VSE z/VSE 4.3 or later One of these Linux on System z operating systems: SUSE Linux Enterprise Server 10 Service Pack 3 together with security update kernel 2.6.16.60-0.57.1 SUSE Linux Enterprise Server 11 Service Pack 1 Red Hat Enterprise Linux 5 Update 5 Red Hat Enterprise Linux 6 z/VSE and Linux on System z are configured as z/VM guests within the same LPAR The IUCV (Inter-User Communication Vehicle) is configured and enabled in both z/VM guests (z/VSE and Linux on System z)8 2011 IBM Corporation

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