Comments inline Niall Litchfield wrote: >I'm - not for the first time bemused - I wonder if anyone can (after >fighting past the screwed up formatting that blogger gave me) shed >light on the results that I have on my site for running identical SQL >on identical hardware (the same machine actually) under Windows XP sp2 >and Fedora Core 3 linux. (incidentally FC3 passed the certified os >checks on install). > > Yes. That probably is because FC3 has direct I/O and async I/O in the kernel, the two facilities that Oracle checks when checking prerequisites. Other then that, welcome to the Dark Side. Experience the power of the farce. >briefly the test is > >create a table with 20k rows. >insert into the table all the rows from itself 6 times > >tune based on the response time (I've used tkprof to generate the >response time profile). > >My linux box seems to be stuck waiting on log_buffer space and whilst >throwing memory at it has helped (I've gone as high as 8mb log buffer >and to my surprise got some marginal improvement over the 1mb I've >documented) it is still half the speed of the same hardware running >windows. some mistake surely. > > No, no mistake there. Async I/O and direct I/O are enabled by default on Win2k and not on FC3. You have to get libaio, as shown below: $ rpm -qa|grep libaio libaio-0.3.102-1 libaio-devel-0.3.102-1 $ That is best achieved by executing "yum install libaio libaio-devel", as root, of course. >My kernel parameters are > >kernel.shmall = 2097152 >kernel.shmmax = 2147483648 >kernel.shmmni = 4096 >kernel.sem = 250 32000 100 128 >fs.file-max = 65536 >net.ipv4.ip_local_port_range = 1024 65000 > > > >because I followed John Smiley's article for the install > >(http://www.oracle.com/technology/pub/articles/smiley_10gdb_install.html) > > > John and Werner give you the default install, which is useless, as such. If you want a speed daemon, you should a) Relink your executable with async option b) Create your data files on a decent file system (like JFS) c) Turn on direct I/O and async I/O by using filesystemio_options parameter in init.ora (or spfile.ora) -- Mladen Gogala Oracle DBA -- //www.freelists.org/webpage/oracle-l