On Wed, Jul 07, 2021 at 03:37:56PM -0700, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> writes: > > > Change a couple of users of strbuf_init() that pass a hint of 8192 to > > pass STRBUF_HINT_SIZE instead. > > > > Both of these hardcoded occurrences pre-date the use of the strbuf > > API. See 5242bcbb638 (Use strbuf API in cache-tree.c, 2007-09-06) and > > af6eb82262e (Use strbuf API in apply, blame, commit-tree and diff, > > 2007-09-06). > > > > In both cases the exact choice of 8192 is rather arbitrary, e.g. for > > commit buffers I think 1024 or 2048 would probably be a better > > default (this commit message is getting this commit close to the > > former, but I daresay it's already way above the average for git > > commits). > > Yes, they are arbitrary within the context of these callers. > > I do not think using STRBUF_HINT_SIZE macro in them is the right > thing to do at all, as there is no reason to think that the best > value for the write chunk sizes in these codepath has any linkage to > the best value for the read chunk sizes used by strbuf_read() at > all. When benchmarking reveals that the best default size for > strbuf_read() is 16k, you'd update STRBUF_HINT_SIZE to 16k, but how > do you tell that it also happens to be the best write buffer size > for the cache-tree writeout codepath (answer: you don't)? Being cc'd on this series, I feel compelled to respond with some review. But I'm in such agreement with what you said here (and downthread, and also in your response to patch 1) that I can only add a lame "me too". :) -Peff
