Posts

My current employer does a lot of really cool systems work that’s covered by NDAs. I recently did some work to integrate a cool open source tool into our workflow. Felt it deserved a blog post. NFS Testing Requires Parallelism. I work for Pure Storage. One of the products we make is a scale-out NFS1 (and S3-compatible) server called FlashBlade. I was asked to test FlashBlade2 performance scaling. I needed to generate NFS read workloads of 15-300 Gigabytes/second. Given that NICs in our lab max out at 100Gbit, (~10GB/s), this required a lab with fast servers and multiple NICs per server. I wanted to make maximum use of hardware to minimize lab space + cost. To make use of multiple NICs I needed multiple NFS connections per NIC. Linux does not make this easy3. ...

This post is about minimizing amount of disk IO and CPU overhead when reading Zip files. I recently saw an article about a new format that was faster than zip. This is quite surprising as to my mind, zip is one of the most flexible and low-overhead formats I’ve encountered. Some googling showed me that over past 11 years people have noticed that Firefox uses optimized zip files. This inspired me to document thinking behind the optimized zip format I implemented in Firefox in the pre-pandemic 2010. I had a lot of fun writing this code, was surprised that I failed to blog about it. ...

In my previous post I made an argument that a modern phone is only as fast as the slowest component: ability of NAND to handle 4k writes. I decided to compare two Android flagships on the opposite ends of random-write-4k benchmark spectrum: Moto Z vs Google Pixel. I wrote a little fio benchmark driver to fill all available device storage with random 4k writes, print perf stats along the way. Idea is to run the benchmark on /data/ partition, then fill all available space by writing to /storage/emulated/0, then do another round of testing on /data. ...

TLDR: You can predict degree of unresponsiveness of a phone via random-write-4k benchmarks. I wish review websites would fill phones to 80-90% prior to running the benchmark, especially on smaller-capacity phones where users are more likely to run out of space. SQLite vs Phone NAND I’ve long held a theory that Android lag is almost directly determined by slowness induced by SQLite transactions. This weekend, while researching phones for a family member, I found some supporting evidence. ...

I spent most of my life in North America, but I have been living this war in Ukraine. My hope is that I can use my past experience and connections to help Ukraine win this war. Recently a friend of mine asked what would be the best way to donate $1000. This got me thinking. Wars are won by convincing the opponent that things are only gonna keep getting worse for them and better for you. Economics is the best way to do that. Germany, Japan could not sustain their aggression in WW2 because they were losing the war economically. USA played a large role in WW2 with amazing logics and manufacturing. ...