Re: [PATCH 1/6] mm: tracking shared dirty pages
From: Andrew Morton <hidden>
Date: 2006-06-22 05:57:05
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lkml
On Mon, 19 Jun 2006 19:52:53 +0200 Peter Zijlstra [off-list ref] wrote: Could we have a changelog for this patch? A list of what-i-changed-since-last-time bullet points is uninteresting and unuseful for the permanent record. Think in terms of some random person in Barcelona who is trying to work upon your code two years hence. The patch should be accompanied by a standalone description of what it does, why it does it and how it does it, thanks.
quoted hunk ↗ jump to hunk
Index: 2.6-mm/include/linux/mm.h ===================================================================--- 2.6-mm.orig/include/linux/mm.h 2006-06-14 10:29:04.000000000 +0200 +++ 2.6-mm/include/linux/mm.h 2006-06-19 14:45:18.000000000 +0200@@ -182,6 +182,12 @@ extern unsigned int kobjsize(const void #define VM_SequentialReadHint(v) ((v)->vm_flags & VM_SEQ_READ) #define VM_RandomReadHint(v) ((v)->vm_flags & VM_RAND_READ) +static inline int is_shared_writable(unsigned int flags) +{ + return (flags & (VM_SHARED|VM_WRITE|VM_PFNMAP)) == + (VM_SHARED|VM_WRITE); +}
Need a comment: what's VM_PFNMAP doing in there.
- if (unlikely(vma->vm_flags & VM_SHARED)) {
+ if (unlikely(is_shared_writable(vma->vm_flags))) {
See, this is an incompatible change. We used to have
if (unlikely((vma->vm_flags & (VM_SHARED|VM_WRITE)) ==
(VM_SHARED|VM_WRITE))) {
in there, only now it has secretly started looking at VM_PFNMAP.
+ vma->vm_page_prot = + __pgprot(pte_val + (pte_wrprotect + (__pte(pgprot_val(vma->vm_page_prot))))); +
Is there really no simpler way?
quoted hunk ↗ jump to hunk
===================================================================--- 2.6-mm.orig/fs/buffer.c 2006-06-14 10:28:52.000000000 +0200 +++ 2.6-mm/fs/buffer.c 2006-06-19 14:45:18.000000000 +0200@@ -2985,6 +2985,7 @@ int try_to_free_buffers(struct page *pag spin_lock(&mapping->private_lock); ret = drop_buffers(page, &buffers_to_free); + spin_unlock(&mapping->private_lock); if (ret) { /* * If the filesystem writes its buffers by hand (eg ext3)@@ -2996,7 +2997,6 @@ int try_to_free_buffers(struct page *pag */ clear_page_dirty(page); } - spin_unlock(&mapping->private_lock); out: if (buffers_to_free) { struct buffer_head *bh = buffers_to_free;
Needs changelogging, please. Performance testing is critical here. I think some was done, but I don't reall what tests were performed, nor do I remember the results. Without such info it's not possible to make a go/no-go decision. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>