http://www.tomshardware.com/reviews/Intel-x25-m-SSD,2012-8.html they say that write IO fluctuates. On 12/12/08, Matthew Wilcox <matthew@xxxxxx> wrote: > On Thu, Dec 11, 2008 at 10:40:41PM +0200, Raz wrote: > > > ________________________________ > > > From: Matthew Wilcox [mailto:matthew@xxxxxx] > > > Sent: Thu 12/11/2008 5:44 AM > > > To: Raz Ben-Yehuda > > > Cc: linux-ide@xxxxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx > > > Subject: Re: Intel X25-M MLC SSD benchmarks > > > > > > On Thu, Dec 11, 2008 at 12:12:37AM +0200, Raz Ben-Yehuda wrote: > > >> I did not want to dive into details because it does not matter. Whether > > >> noop,deadline, deadline parameters... > > >> As for the controller I used 4 different controllers. Adaptec,AHCI and > > >> Intel as Integrated chips on the 1025W-UR supermicro motherboard, and a > > >> 4-th controller SuperMicro UIO Adaptec aac card. > > >> All gave same results for most dd writes commands. > > >> dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct , and many > > >> other variants such erase block size ( 128K ) , several erase block size > > >> and so on. Kernel is 2.6.18-8.el5. > > > > > >>>OK, I suspect you aren't giving the drive enough work to do for it to > > >>>perform at its best. Try doing something like this: > > > > > >>>for i in $(seq 0 9); do \ > > > >> dd if=/dev/zero of=/dev/sda bs=1M count=1000 oflag=direct \ > > > >> seek=$(($i * 1000)) & \ > > >>>done > > > > > did that. nothing. also, I would like to note that IO flow is quite > > weird.iostats reports 70GB/s in the first few seconds, and then it > > degrades to 20 > > MB/s and less. could it be that I am not erase-block aligment ? > > > That doesn't sound likely to me. Erase block size isn't a huge issue > with these drives. I've been trying to replicate your problem, but I'm > not having any luck; unfortunately I only have access to an X25-E drive > (not an X25-M) and I'm seeing 175-185MB/s when it's attached to an AHCI > controller, just with a single dd (I haven't even played with the > elevator). I'm trying to get hold of an X25-M drive, but I don't know > when I'll receive one. > > > > how does SSD aligments interacts with a controller ? > > > Controllers can generally send down large enough IOs that it isn't a > problem. And the Intel SSDs are smart enough that you shouldn't have to > align to erase block boundaries to make them go fast. > > > -- > > Matthew Wilcox Intel Open Source Technology Centre > "Bill, look, we understand that you're interested in selling us this > operating system, but compare it to ours. We can't possibly take such > a retrograde step." > -- 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
