Re: [PATCH] tools/mm: Add madvise tool

[Kiryl Shutsemau <kirill@shutemov.name>]

On Fri, Sep 05, 2025 at 12:19:11PM +0200, David Hildenbrand wrote:
> On 04.09.25 19:57, kirill@shutemov.name wrote:
> > From: Kiryl Shutsemau <kas@kernel.org>
> > 
> > Add a simple tool that allows to issue an advice on a process or a file.
> > 
> > It can be useful to experiment with effects of an advice on a workload
> > without modifying the workload itself.
> > 
> > Only supports advices available for process_madvise().
> > 
> > Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
> > ---
> 
> > +	if (pid) {
> > +		struct iovec vec = {
> > +			.iov_base = (void *)start,
> > +			.iov_len = end - start,
> > +		};
> > +		ssize_t ret;
> > +
> > +		ret = process_madvise(fd, &vec, 1, advice, 0);
> > +		if (ret < 0)
> > +			perror("process_madvise"), exit(-1);
> > +
> > +		if ((unsigned long)ret != end - start)
> > +			printf("Partial advice occurred. Stopped at %#lx\n", start + ret);
> > +	} else {
> > +		unsigned long addr, hpage_pmd_size;
> > +		void *p;
> > +		int ret;
> > +
> > +		hpage_pmd_size = read_pmd_pagesize();
> > +		if (!hpage_pmd_size) {
> > +			printf("Reading PMD pagesize failed");
> > +			exit(-1);
> > +		}
> > +
> > +		// Allocate virtual address space to align the target mmap to PMD size
> > +		// Some advices require this.
> 
> I assume the kernel coding-style applies to tools/ as well, so
> 
> /*
>  * ...
>  */

I thought C99 comments are fine now, no? Like slab_common.c uses them.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov