Re: [PATCH next 0/2] THP COW support for private executable file mmap

David Hildenbrand (Red Hat)
2025-12-15T14:26:32Z

On 12/15/25 15:00, Matthew Wilcox wrote:
> On Mon, Dec 15, 2025 at 08:34:05PM +0800, Zhang Qilong wrote:
>> This patch series implementate THP COW for private executable file
>> mmap. It's major designed to increase the iTLB cache hit rate for
>> hot patching application, and we add a new sysfs knob to disable or
>> enable it.
>
> You're going to have to provide data to get this patch in. We've
> deliberately not done this in the past due to memory consumption overhead.
> So you need to prove that's now the wrong decision to make.
>
> Microbenchmarks would be a bare minimum, but what are really needed are
> numbers from actual workloads.

In addition, the sysfs toggle is rather horrible. It's rather clear that
this is not a system-wide setting to be made, as you likely only want
that behavior (if at all ...) for a handful of special processes I assume?

--
Cheers

David