Hello, Liam. As you pointed out, I did enough testing in the userspace and in previous versions of the kernel, but I was surprised that a syntax error occurred in making newest patch because of my careless mistake. I will be careful not to make this mistake again. And I am going to study the low memory situation in kernel space in more detail. Thank you very much for your detailed answer and explanation. Best regards, JaeJoon Jung On Mon, 3 Jun 2024 at 21:29, Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> wrote: > > * JaeJoon Jung <rgbi3307@xxxxxxxxx> [240602 05:06]: > > Hello, Liam. > > Thank you very much for the detailed answer and explanation. > > > > I tested this patch in userspace. > > In user space, this phenomenon always occurs when kmem_cache_alloc() > > is executed to allocate a new node. > > This is expected in the userspace test program. We test the error path > most frequently, with only a bypass for those who wish to test an > initial success - such as preallocations. I was concerned about the > testing since your first patch had a syntax error with a correction > quickly after. It is good news that you were able to find and use the > maple tree testing framework, though. > > > I will try to test it in more detail in kernel space. > > If you test in kernel space, you will have to hit a low memory scenario > to see a difference. stress-ng would probably help. > > > I will also refer to the notes from the email list you shared > > and send results once a more clear analysis has been made. > > I don't think you need to continue with this work as you will find that > the low memory situation is going to be rare and in a very slow path > already. > > Thanks, > Liam
