From: Martin Fick Date: Wed, 07 Jan 2026 22:58:36 GMT Subject: Re: Slow git pack-refs --all Message-ID: In-Reply-To: > From: Patrick Steinhardt Sent: Wednesday, January 7, 2026 4:42 AM On Tue, Jan 06, 2026 at 11:02:19PM +0000, Martin Fick wrote: > > From: Patrick Steinhardt Sent: Monday, January 5, 2026 11:53 PM > > > Did you try using perf(1) to profile the process and generate a flame > > > graph from it? That should likely make it immediately obvious where Git > > > is spending all of its time. > > > > I will pursue this. Unfortunately this might be difficult on this > > particular server. > > True, on the server side this can be a bit tricky. I ran perf, and got a flame graph, I am not sure what the best way to share that is, but I will try to summarize what looked important: About one third of the time is in this section: libc-2.17.so 32.5% _memcmp_sse4_1 29.8% page_fault 7.23% ... I am not really sure what that is doing? Another third is doing: unpack_object_header_buffer 30% page_fault 26.9% ... nfs_read_page 10% Which could very well be looking at the headers of objects to see if they are tags needing to be peeled? And the remaining third was a bit all over the place with small sections, the largest two of those sections being: packed_refs_store_create ~8.7% unknown 4.4% memchr 4.4% page_fault 4.4% nth_packed_object_offset 7% page_fault 3.2% This was way less informative (to me) then I would have hoped. :( Maybe this means more to you? It does look like a lot of page_faults, likely due to the use of mmap? -Martin