From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate001.proxmox.com (gate001.proxmox.com [IPv6:2a0f:8001:1:32::40]) by lore.proxmox.com (Postfix) with ESMTPS id A403B1FF13A for ; Wed, 08 Jul 2026 10:44:49 +0200 (CEST) Received: from gate001.proxmox.com (localhost.localdomain [127.0.0.1]) by gate001.proxmox.com (Proxmox) with ESMTP id 740F421448; Wed, 08 Jul 2026 10:44:49 +0200 (CEST) Message-ID: <1869af1c-2292-4539-9a04-ee0a1cb96b82@proxmox.com> Date: Wed, 8 Jul 2026 10:44:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH datacenter-manager 2/3] ui: d/rules: use thin instead of fat LTO To: =?UTF-8?Q?Fabian_Gr=C3=BCnbichler?= , Dominik Csapak , pdm-devel@lists.proxmox.com, Thomas Lamprecht References: <20260706114822.2751086-1-d.csapak@proxmox.com> <20260706114822.2751086-3-d.csapak@proxmox.com> <1783433095.x62omid41h.astroid@yuna.none> <5b842f53-3059-4ac2-9e7a-4a7a04132ace@proxmox.com> <1783494290.vpra89xkg7.astroid@yuna.none> Content-Language: en-US, de-AT From: Robert Obkircher In-Reply-To: <1783494290.vpra89xkg7.astroid@yuna.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1783500247012 X-SPAM-LEVEL: Spam detection results: 0 DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment (newer systems) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Message-ID-Hash: ZINS4QKDI67XXHHPX5ZJL6OMKM573ON2 X-Message-ID-Hash: ZINS4QKDI67XXHHPX5ZJL6OMKM573ON2 X-MailFrom: r.obkircher@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox Datacenter Manager development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On 08.07.26 09:12, Fabian Grünbichler wrote: > On July 7, 2026 11:53 pm, Thomas Lamprecht wrote: >> 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. > Most perf related documentation seems to say codegen-units=1 and LTO=fat > are the way to go if you want to optimize for performance, though > whether that is true for wasm I don't know (the documentation there is > quite messy/outdated). > > AFAIK, it's how projects optimizing for performance build their release > binaries (i.e., firefox and rustc/cargo upstream both ship their > binaries built that way - they also tack on profile based optimizations > for even more gains). Would be interesting to test whether for PBS we'd > see benefits doing that as well? > The drawback is that PGO would make our builds non-reproducible. > >