On ven, 2006-02-03 at 17:33 +0100, Christophe Varoqui wrote: > On Sun, Jan 22, 2006 at 05:43:24PM +0000, Alasdair G Kergon wrote: > > On Wed, Jan 18, 2006 at 04:41:57PM -0500, David Wysochanski wrote: > > > I'm wondering where the value of 1000 came from, and > > > > Thin air. > > > > > whether that's really a good default. > > > > Unlikely. > > > > That's why we made it configurable - to make it easy to try out > > different values and use whatever you find best. > > > I'm less and less confident we can find good figures, even for a specific workload. > Here is another round of numbers. > > Is there still a plan for pluging the elevator in the devmapper device ? > This could help us produce predictable figures (the ones admins like). > I read in the LWN article titled "Request Queues I" at http://lwn.net/Articles/27055/ that : "One request queue can be shared across multiple physical drives, but the normal usage is to create a separate queue for each drive." Is it still the case ? Would it be better to coalesce the different paths request queues upon multipath map load and re-split them upon unload ? > Regards, > cvaroqui > > Hardware : > - 2x2Gb/s Qlogic HBA > - 1x100GB Vraid1 in a 2C2D EVA3000 StorageWorks array > > Test : > - 1 streaming read at a time > - Variations of rr_min_io and dd blocksize > > Results : > > min_io dd block size (kB) > 4 8 16 32 64 128 256 512 1024 > > 8 111 53 51 47 32 59 50 41 61 > 16 28 79 46 55 112 52 83 68 61 > 32 41 33 46 31 116 36 75 106 37 > 64 48 36 67 36 81 54 71 53 47 > 128 46 46 57 54 66 54 66 59 44 > 256 56 50 63 63 69 53 57 55 63 > 512 56 49 55 58 66 60 88 56 57 > 1024 62 54 70 62 91 82 89 61 61 > > Script used : > #!/bin/bash > > MULTIPATH=/root/foo/multipath/multipath > DEV=/dev/mapper/mpath1 > DD="sg_dd sync=1 time=1 dio=1" > SIZE="1024*1024" > MINIO="8 16 32 64 128 256 512 1024" > BS="4 8 16 32 64 128 256 512 1024" > > # > # @1 : desired min_io > # > function set_minio > { > sed s/XX/$1/ /root/multipath.conf > /etc/multipath.conf > $MULTIPATH $MULTIPATH_OPT >/dev/nul > } > > # header > echo "0 $BS" > > for minio in $(echo $MINIO) > do > set_minio $minio > echo -n "$minio " > for bs in $(echo $BS) > do > count=$(($SIZE/$bs)) > echo -n "$($DD if=$DEV of=/dev/null bs=${bs}k count=${count} 2>&1|head -1|awk '{print $8}') " > done > echo > done > > -- > > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
