Re: [PATCH datacenter-manager 2/3] ui: d/rules: use thin instead of fat LTO

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

Am 07.07.26 um 16:06 schrieb Fabian Grünbichler:
> On July 6, 2026 1:44 pm, Dominik Csapak wrote:
>> fat LTO merges all LLVM modules into a single unit for optimizing.
>> Changing this to thin LTO increases the uncompressed binary size by 1.59
>> MiB (+11%) (compressed +192KiB/+4.6%) but save us ~160s (-40%) of (wall)
>> build time during a 'make deb'.
> but what are the effects on runtime performance? the same question also
> applies to the next patch, a single codegen unit increases the amount of
> optimizations the compiler can do..

FWIW, https://docs.wasmtime.dev/examples-minimal.html states:

"""
Note that with LTO using a single codegen unit may only have marginal benefit.
If not using LTO, however, a single codegen unit will likely provide benefit over the default 16 codegen units.
"""

If that (still) holds, we currently do the worst of both worlds compile
time wise while not really profiting from this. I'd probably try dropping
overriding codegen units first (we do not lower that on performance other
(non-wasm) critical code either, e.g. PBS.