On Sat, Jan 20, 2007 at 10:16:15PM +0200, Ismail Dönmez wrote: > 20 Oca 2007 Cts 22:10 tarihinde, Tim Schmielau ??unlar?? yazm????t??: > [...] > > > > Note that these dd "benchmarks" are completely bogus, because the data=20 > > doesn't actually get written to disk in that time. For some enlightening=20 > > data, try > > > > time dd if=3D/dev/zero of=3D/tmp/1GB bs=3D1M count=3D1024; time sync > > > > The dd returns as soon as all data could be buffered in RAM. Only sync=20 > > will show how long it takes to actually write out the data to disk. > > also explains why you see better results is writeout starts earlier. > > Still not that bad: > > [~]> time dd if=/dev/zero of=/tmp/1GB bs=1M count=1024;sync > 1024+0 records in > 1024+0 records out > 1073741824 bytes (1,1 GB) copied, 53,3194 s, 20,1 MB/s > > real 0m53.517s > user 0m0.003s > sys 0m3.193s
No, your measure is wrong because time measures "dd" and sync is done after. Either use Tim's method (time sync) or the one I proposed in previous mail (time dd | sync). Anyway, in your situation with a very small buffer, this should not change by more than half a second or so. Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
