Plumbing through patchpaddingalign from UAT to UnrealPak

Development Pipeline & Plugins
, ,
1

This question was created in reference to: [Solution for large Steam patch sizes when pak compression is [Content removed]

In the above question, Per Larsson of Epic Games wrote:

I’ve created Jira to update the docs and to expose the compression block size in a better way.

We’d like to set our patchpaddingalign to be optimal for distribution through Steam, but it seems from reading the code of UE5.4 that the above Jira wasn’t completed for this, so it looks like the only ways to set the compression block alignment whilst building with UAT BuildCookRun is to either:

  1. Make an engine mod as per the suggestion in the thread
  2. Use the iostorepatchpaddingalign param

I’m not hugely fond of either of these options, as we don’t want to introduce engine mods that aren’t strictly necessary, and there’s a comment attached to the usage of iostorepatchpaddingalign that states:

// Temporary, this command-line allows us to explicitly override the value otherwise shared between pak building and iostoreDo you know when the plan to expose the compression block size might come to fruition, please? And do you know how temporary the iostorepatchpaddingalign parameter is and when it might get removed from under us? Do you have any other guidance for how best we can optimize our patch sizes that avoids the use of an engine mod or a temporary CLI arg?

2

Hey Elliot,

unfortunately that request never made it into a Jira.

I’ve created a bug report now as UE-272843 and it should be visible in the public issue tracker here soon.

Given our current priorities I don’t think this will make it into 5.6, so if you want to set those parameters you’ll need to use the temporary one for now.

Given that the fix has low priority I don’t expect -iostorepatchpaddingalign to get removed soon, and if it’s removed it will likely be in combination with a fix for that Jira and hopefully a better way to specify it.

Unfortunately I don’t have much other advice for patch sizes on steam. Uncompressed can definitely help, so it’s worth trying those out. If the larger padding makes a big difference then this is likely the best approach if you also want compression.

You could try chunking or other approaches to manage your content in a way that minimizes modifications to certain files, but I don’t have any actual numbers on whether this will make a big impact for the steam patching algorithms.

Best,

Sebastian