On Tue, 2009-02-17 at 01:43 +0300, Edward Shishkin wrote: > > How much performance gain do you see by avoiding that radix tree op? > > > > Nop. We want to use it with extended semantics. > All dirty pages are divided into 2 categories: > > A) tagged in the radix tree (with PAGECACHE_TAG_DIRTY). > B) captured by atoms (usual linked lists). > > reiser4_writepages() looks for pages of "A" in the radix tree > and moves them to "B". set_page_dirty_notag(), introduced by > my patch, is needed for pages of "B". > > If "B" is empty, then we get the traditional semantics with > regular ->writepages(). > > That's all! Ah, indeed. I had not considered such a scheme. > Add set_page_dirty_notag() to the core library to enable > extended functionality of radix tree attached to inode->i_mapping. > > Signed-off-by: Edward Shishkin<edward.shishkin@xxxxxxxxx> Looks good to me Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > --- > include/linux/mm.h | 1 + > mm/page-writeback.c | 36 ++++++++++++++++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > --- mmotm.orig/include/linux/mm.h > +++ mmotm/include/linux/mm.h > @@ -841,6 +841,7 @@ int redirty_page_for_writepage(struct wr > struct page *page); > int set_page_dirty(struct page *page); > int set_page_dirty_lock(struct page *page); > +int set_page_dirty_notag(struct page *page); > int clear_page_dirty_for_io(struct page *page); > > extern unsigned long move_page_tables(struct vm_area_struct *vma, > --- mmotm.orig/mm/page-writeback.c > +++ mmotm/mm/page-writeback.c > @@ -1248,6 +1248,42 @@ int __set_page_dirty_nobuffers(struct pa > EXPORT_SYMBOL(__set_page_dirty_nobuffers); > > /* > + * set_page_dirty_notag() -- similar to __set_page_dirty_nobuffers() > + * except it doesn't tag the page dirty in the page-cache radix tree. > + * This means that the address space using this cannot use the regular > + * filemap ->writepages() helpers and must provide its own means of > + * tracking and finding non-tagged dirty pages. > + * > + * NOTE: furthermore, this version also doesn't handle truncate races. > + */ > +int set_page_dirty_notag(struct page *page) > +{ > + struct address_space *mapping = page->mapping; > + > + if (!TestSetPageDirty(page)) { > + WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); > + if (mapping_cap_account_dirty(mapping)) { > + /* > + * The accounting functions rely on > + * being atomic wrt interrupts. > + */ > + unsigned long flags; > + local_irq_save(flags); > + __inc_zone_page_state(page, NR_FILE_DIRTY); > + __inc_bdi_stat(mapping->backing_dev_info, > + BDI_RECLAIMABLE); > + task_dirty_inc(current); > + task_io_account_write(PAGE_CACHE_SIZE); > + local_irq_restore(flags); > + } > + __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); > + return 1; > + } > + return 0; > +} > +EXPORT_SYMBOL(set_page_dirty_notag); > + > +/* > * When a writepage implementation decides that it doesn't want to write this > * page for some reason, it should redirty the locked page via > * redirty_page_for_writepage() and it should then unlock the page and return 0 -- To unsubscribe from this list: send the line "unsubscribe reiserfs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html