On Sun, 30 Dec 2007, Marco Costalba wrote: > > Sorry to ask, but just out of curiosity, what were the reasons to > choose zlib compression algorithm among the possible ones? It's out there, it's common, it's stable, and it's very good "on average". In other words, other compression methods tend to be worse. No, zlib isn't perfect, but it was the obvious default choice for me (I've used it before, we use it in the kernel, it's usually good enough), and I actually expected the SHA1 to be the bigger expense. Even today, I don't really know of a better compression choice, despite now being more aware of how critical uncompression performance is. And quite honestly I'm not really even sure that the performance downside is entirely about zlib itself: I suspect a lot of the reason zlib shows up in the profiles is that the source data is usually cold in the cache, so it probably takes a lot of cache misses (it also will take all the page faults!). Quite possibly, the cache miss costs dominate over any algorithmic costs. Linus - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
