Re: AW: AW: AW: WAL does not recover gracefully from ou t-of -dis k-sp ace

More numbers, these from a Powerbook G3 laptop running Linux 2.2:

[tgl(at)g3 tmp]$ uname -a
Linux g3 2.2.18-4hpmac #1 Thu Dec 21 15:16:15 MST 2000 ppc unknown

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_DSYNC -DBLOCKS=1 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m32.418s
user 0m0.020s
sys 0m14.020s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_DSYNC -DBLOCKS=4 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m10.894s
user 0m0.000s
sys 0m4.030s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_DSYNC -DBLOCKS=8 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m7.211s
user 0m0.000s
sys 0m2.200s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_DSYNC -DBLOCKS=32 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m4.441s
user 0m0.020s
sys 0m0.870s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_DSYNC -DBLOCKS=64 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m4.488s
user 0m0.000s
sys 0m0.640s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_ODSYNC -DBLOCKS=1 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m3.725s
user 0m0.000s
sys 0m0.310s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_ODSYNC -DBLOCKS=4 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m3.785s
user 0m0.000s
sys 0m0.290s

[tgl(at)g3 tmp]$ gcc -Wall -O -DINIT_WRITE -DUSE_ODSYNC -DBLOCKS=64 tfsync.c
[tgl(at)g3 tmp]$ time ./a.out

real 0m3.753s
user 0m0.010s
sys 0m0.300s

Starting to look like we should just use ODSYNC where available, and
forget about dumping more per write ...

regards, tom lane