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.

Zhang Qilong (2):
  mm/huge_memory: Implementation of THP COW for executable file mmap
  mm/huge_memory: Add sysfs knob for executable THP COW

 Documentation/admin-guide/mm/transhuge.rst |   8 ++
 include/linux/huge_mm.h                    |   5 +
 mm/huge_memory.c                           | 105 ++++++++++++++++++++-
 mm/memory.c                                |  13 +++
 4 files changed, 130 insertions(+), 1 deletion(-)

-- 
2.43.0

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.

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