[ofa-general] iSer and Direct IO

[Cameron Harr]

Joe Landman wrote:
> This is only 8 GB of IO.  It is possible that (despite dio) you are 
> caching.  Make the IO much larger than RAM.  Use a count of 128m or so.

This is going to sound dumb, but I thought I had 4 GB of RAM and thus 
intentionally used a file size 2x my physical RAM. As it turns out, I 
have 32GB of RAM on the box (4G usually shows up as 38.... and I just 
saw the 3). Anyway, with a 64GB file the numbers are looking more 
accurate (and even low):
393.3 MB/s
> We have found dd to be quite trustworthy with [oi]flag=direct.
I like it too. At any rate, I'm going to need to do some new testing to 
avoid the ram size (might just set a mem limit on the boot line).

There's still a bit of a discrepancy between IOP performance with iSer 
and srpt. Has anyone else done comparisons with the two? I think Erez 
was hoping to get some numbers before too long.
Cameron