Thursday May 31, 2007

Because the Solaris TCP stack's default settings are optimized more for bandwidth than latency, Solaris HPC users and others with latency requirements may find the following note useful.

Using default TCP and driver settings on Solaris 10, MPI zero-length ping-pong latencies are measured to be about 60us on Solaris versus 25-30us on Linux. The issue is a result of Solaris being tuned by default for bulk transfers and reduced processor utilization through the use of interrupt blanking or interrupt coalescing. Turning off blanking reduces the Solaris latencies to be on par with those of Linux. It also increases processor utilization and will reduce performance on large message transfers, so there is a tradeoff to be aware of.

To turn off blanking on a bge interface, add the following lines to /etc/system:

set bge:bge_rx_count_norm=1
set bge:bge_rx_ticks_norm=1
set dld:dld_opt = 2

To turn off blanking on an e1000g interface, use a combination of ndd tunables and entries in the e1000g.conf file. This support is currently available under Open Solaris and will be available for Solaris 10 in a future update release. The config file entries are:

intr_adaptive=0,0,0,0,0,0,0,0;
intr_throttling_rate=0,0,0,0,0,0,0,0;

The ndd commands (which are not strictly related to blanking, but may improve application performance in some instances) are:

ndd -set /dev/e1000g0 tx_interrupt_enable 0
ndd -set /dev/e1000g0 rx_bcopy_threshold 128

Sun's new dual-ported mulithreaded 10 GbE interface card, can be tuned by adding the following lines to the nxge.conf file:

rxdma-intr-time=0;
rxdma-int-pkts=0;

Sunday May 06, 2007

Saturday May 05, 2007

Back in January, I took the Superhero Personality Quiz. Today, I took the same quiz on behalf of Sun, wondering which superhero would best match Sun's corporate personality. Just giving you the answer wouldn't be any fun so I kept notes on how I answered each question. Obviously, this is one engineer's personal view of Sun. You might try this yourself and see which superhero you think Sun most resembles.

Here are the questions and my answers.

Iron Man 75% Spider-Man 65% Robin 65% Superman 60% Green Lantern 60% The Flash 55% Catwoman 45% Supergirl 42% Wonder Woman 27% Hulk 20% Batman 20%

Inventor. Businessman. Genius.

Friday May 04, 2007

I know a few people who use Delicious Library to catalogue their books, music, and movies. Mostly to keep track of what they have and what they've lent out. It's a slickly done application with a nice look and feel and several input methods, including support for barcode scanners and using a Mac's iSight to capture barcodes. I was tempted to try DL, but decided instead to try Library Thing.

Library Thing works with books only. It lacks much of the polish of Delicious Library. It does work with barcode scanners like the :CueCat. It's real saving grace is that it is web-based. By storing libraries in the network, Library Thing creates a community of book lovers. And with access to the libraries of 190,000 members containing almost two million unique works, Library Thing can suggest books you might like based on similar holdings in similar libraries, or suggest books that are tagged similarly to books you own. It's also fun to see I have some unique books -- books that none of the other 190,000 members have in their libraries. Likewise, it's a kick to find members who share my interests and own some of the odder books I have in my library.

Take a short tour of Library Thing to learn more. You Delicious Library users (and others) can import your libraries into Library Thing if you'd like to experience the community aspects of the site.

I bought a :CueCat for $15 from Library Thing and have started scanning. As of this writing, I have scanned only 235 books, but if you like, you can see what I've loaded so far.

Thursday May 03, 2007

I stopped at the Palo Alto Apple store yesterday to see if my battery was eligible for replacement under Apple's latest replacement program. With a cycle count of about 180 and a current battery life of about 2.5 hours even after applying the latest battery software update, I thought it was worth a try. And it was, eventually.

The genius/tech at the Palo Alto store first said I wasn't eligible based on my machine's serial number and that of the battery. He determined this by removing the battery from my sleeping machine (which kernel panic'ed later as a result, but now seems okay.) After I told him I had come to the store based on this article, which didn't seem to have any relation to serial numbers, he gave me a new battery.

As we were finishing, he mentioned that my machine was out of warranty. Which wasn't true, since I had bought Apple Care coverage when I purchased the laptop. This was the second time Apple has lost track of this coverage. I called 1-800-APL-CARE and they fixed the problem, though it did take more than 15 minutes on the phone.

For those keeping track, here are the issues I've had so far with my Mac Book Pro. Click on a summary to read the full blog entry.

Our group (SPARC Platform Software) has just released V1.0 of Logical Domains (LDoms) for the UltraSPARC T1 processor. With LDoms virtualization, you can run 32 separate Solaris instances on a single UltraSPARC-T1 based system. Customers with Sun Fire T1000 and T2000 systems or with Netra T2000 or CP3060 systems will find the downloadable bits here.

My colleague, Ashley Saulsbury, has more details about LDoms and virtualization on his blog. Or check out the official product page.

Did I mention LDoms software is free? Yes, I guess I did. :-)