From: Johannes Schindelin Date: Tue, 05 May 2026 20:54:59 GMT Subject: Re: [PATCH v2 08/11] test-tool synthesize: precompute pack for 4 GiB + 1 Message-ID: <53431a2a-a0e8-1dd1-9ebd-cbaebc769a39@gmx.de> In-Reply-To: Hi Stolee, On Tue, 5 May 2026, Derrick Stolee wrote: > On 5/4/2026 1:08 PM, Johannes Schindelin via GitGitGadget wrote: > > From: Johannes Schindelin > > > Benchmarks generating a 4 GiB + 1 pack (3 runs each, SHA1DC on > > x86_64): > > > > generic path: 88s / 81s / 140s > > fast path: 14s / 13s / 15s > > > > On CI, where t5608 currently takes 200-850 seconds depending on the > > job, the fast path cuts the pack-generation phase from minutes to > > seconds, leaving only the clone operations themselves. > > Are these numbers accurate for the patch position in the series? Unfortunately, yes. > The previous change replaced SHA1DC with the unsafe version, which > gained similar performance improvements. I'd be interested to see > the numbers for both enabled at the same time. The problem is that in many (most?) cases, the "unsafe" version is the _same_ as the safe version, i.e. SHA1DC. Only the `linux-TEST-vars` job on CI (and most notably, _not_ in the `win-*` jobs) has a fast "unsafe" version by default. So if I build the revision as per the previous patch on Windows, I get no performance benefit whatsoever. That's what my lament about not being able to link OpenSSL was all about. Ciao, Johannes