On Thu, 12 May 2022 07:03:47 +0000 cgel.zte@xxxxxxxxx wrote:
> From: xu xin <xu.xin16@xxxxxxxxxx>
>
> To use KSM, we have to explicitly call madvise() in application code,
> which means installed apps on OS needs to be uninstall and source code
> needs to be modified. It is inconvenient.
>
> In order to change this situation, We add a new proc file ksm_force
> under /proc/<pid>/ to support turning on/off KSM scanning of a
> process's mm dynamically.
>
> If ksm_force is set to 1, force all anonymous and 'qualified' VMAs
> of this mm to be involved in KSM scanning without explicitly calling
> madvise to mark VMA as MADV_MERGEABLE. But It is effective only when
> the klob of /sys/kernel/mm/ksm/run is set as 1.
>
> If ksm_force is set to 0, cancel the feature of ksm_force of this
> process and unmerge those merged pages belonging to VMAs which is not
> madvised as MADV_MERGEABLE of this process, but leave MADV_MERGEABLE
> areas merged.
It certainly seems like a useful feature.
> Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
> Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx>
> Reviewed-by: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx>
> Reviewed-by: wangyong <wang.yong12@xxxxxxxxxx>
> Reviewed-by: Yunkai Zhang <zhang.yunkai@xxxxxxxxxx>
> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Suggested-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
This patch doesn't have your Signed-off-by:. It should, because you
were on the delivery path. This is described in
Documentation/process/submitting-patches.rst, "Developer's Certificate
of Origin".
I'll queue it for some testing but please do resend with that tag.
> +/* Check if vma is qualified for ksmd scanning */
> +static bool ksm_vma_check(struct vm_area_struct *vma)
I have trouble with "check" names, because the name doesn't convey what
is being checked, nor does the name convey whether it's checking for
truth or for falsity.
I suggest that "vma_scannable" is a more informative name. It doesn't
need the "ksm_" prefix as this is a static file-local function.
See, with the name "vma_scannable", that comment which you added is
barely needed.
--- a/mm/ksm.c~mm-ksm-introduce-ksm_force-for-each-process-fix
+++ a/mm/ksm.c
@@ -335,7 +335,7 @@ static void __init ksm_slab_free(void)
}
/* Check if vma is qualified for ksmd scanning */
-static bool ksm_vma_check(struct vm_area_struct *vma)
+static bool vma_scannable(struct vm_area_struct *vma)
{
unsigned long vm_flags = vma->vm_flags;
@@ -551,7 +551,7 @@ static struct vm_area_struct *find_merge
if (ksm_test_exit(mm))
return NULL;
vma = vma_lookup(mm, addr);
- if (!vma || !ksm_vma_check(vma) || !vma->anon_vma)
+ if (!vma || !vma_scannable(vma) || !vma->anon_vma)
return NULL;
return vma;
}
@@ -2328,7 +2328,7 @@ next_mm:
goto no_vmas;
for_each_vma(vmi, vma) {
- if (!ksm_vma_check(vma))
+ if (!vma_scannable(vma))
continue;
if (ksm_scan.address < vma->vm_start)
ksm_scan.address = vma->vm_start;
_
