kenneth johansson wrote: > On Mon, 2008-10-13 at 18:33 -0700, Grant Grundler wrote: >> On Mon, Oct 13, 2008 at 3:19 PM, kenneth johansson <ken@xxxxxxxxx> wrote: >> ... >>>> Can you try "dd oflag=direct if=/dev/null of=/dev/sdb bs=64k"? >>> I changed to use O_DIRECT and it's much more consistent now. 69-75 with >>> 74 about 95% of the time. >> That's low but it could be worse. Many things can contribute to slow >> disks. > Well my main problem was that it was fluctuating so much that can't be > right. > >> Favorites are overtemp (See SMART field 194) and vibration (no >> measurement possible w/o special equipment). "dd" isn't exactly a >> performance application until one uses really big block sizes (1MB or >> larger). > All my numbers comes from using 1MB blocks. but I'm not using dd. > After removing the logic that actually put some data into the buffers I > do get about 105 MB/sec using O_DIRECT. I'm doing a full disk write now > to get a reference plot. Not using O_DIRECT should be almost identical. > > >>> the disk is supposed to have 105 115 sustained >>> data rate. >> Where did 105-115 number come from? > datasheet . they listed two drives in the same column so that was not > the range it was sustained OD and the model I have max out at 105. Can you try deadline scheduler? -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
