From: Paul H. Hargrove (PHHargrove_at_lbl_dot_gov)
Date: Mon Jan 08 2007 - 09:20:38 PST
I do not know of any explanation for "slow" I/O in restarted processes. There is absolutely nothing in BLCR that intercepts or otherwise modifies the handling of sockets (or any other file descriptor) either before a checkpoint or after a restart. -Paul Dai MIKURUBE wrote: > Hi, > > Sorry, I think the following problem is occured by my extension > for migrating sockets. I'll check my code. > > > But I'd still like to know > "Do restarted processes have any bottleneck in I/O?" > > I'm waiting for reply. Thanks. > > Dai MIKURUBE wrote: > >> Hi, >> >> I asked a few questions about BLCR some days ago. >> Today, I have another question. >> >> I'm trying to migrate some networked applications. >> At first, I tried creating sockets after restart as follows: >> >> 1) start Apache 1.3 >> # cr_run /usr/sbin/apache >> >> 2) checkpoint the root process of Apache >> # cr_checkpoint --term (process number of Apache root process) >> >> 3) restart the checkpoint file >> # cr_restart context.(process number of Apache root process) >> >> 4) send HUP signal to the process >> # kill -HUP (process number of Apache root process) >> >> 5) access to the Apache process with httperf >> # httperf .... >> >> I have succeeded only accessing Apache web server, >> but the access is too slow... >> >> >> My question is : >> >> "Are there some bottlenecks in handling file descriptors, files, >> and sockets of *restarted* processes?" >> >> or >> >> "Can restarted processes generates many new sockets?" >> >> >> The connections created by restarted processes look strange. >> Though the client "httperf" is waiting for Apache's reply, >> the result of "netstat -a" usually says no connection is established. >> >> "netstat -a" says that some connections is established in a moment, >> but the established connections vanish in a moment. >> >> But, finally, httperf says almost all connections replyed correctly. >> (Reply status of All connections are 2xx) >> >> >> Do you know of such behavior of BLCR? >> and do you have some ways to avoid these problems? >> > -- Paul H. Hargrove PHHargrove_at_lbl_dot_gov Future Technologies Group HPC Research Department Tel: +1-510-495-2352 Lawrence Berkeley National Laboratory Fax: +1-510-486-6900