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Date: Fri, 8 Oct 2010 03:08:56 -0400 From: Christoph Hellwig <hch@....de> To: Dave Chinner <david@...morbit.com> Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 04/18] fs: Implement lazy LRU updates for inodes. Looks good, Reviewed-by: Christoph Hellwig <hch@....de> A few nipicks on the comments or lack thereof below: > @@ -489,8 +484,15 @@ static void prune_icache(int nr_to_scan) > > inode = list_entry(inode_unused.prev, struct inode, i_list); > > - if (inode->i_state || atomic_read(&inode->i_count)) { > + if (atomic_read(&inode->i_count) || > + (inode->i_state & ~I_REFERENCED)) { > + list_del_init(&inode->i_list); > + percpu_counter_dec(&nr_inodes_unused); > + continue; > + } > + if (inode->i_state & I_REFERENCED) { > list_move(&inode->i_list, &inode_unused); > + inode->i_state &= ~I_REFERENCED; > continue; I think this code could use some comments explaining the lazy LRU scheme. > - if (inode != list_entry(inode_unused.next, > - struct inode, i_list)) > - continue; /* wrong inode or list_empty */ > - if (!can_unuse(inode)) > + /* > + * if we can't reclaim this inod immediately, give it > + * another pass through the free list so we don't spin > + * on it. s/inod/inode/ > + > + /* > + * We avoid moving dirty inodes back onto the LRU now because I_FREEING > + * is set and hence writeback_single_inode() won't move the inode > + * around. > + */ > + if (!list_empty(&inode->i_list)) { > + list_del_init(&inode->i_list); > + percpu_counter_dec(&nr_inodes_unused); > + } > + The comment is a bit misleading. We do not only avoid moving it to the LRU, but actively delete the inode from the LRU here. I don't think the I_FREEING check isn't the only reason - the LRU code traditionally couldn't deal with unlinked inodes at all, although the switch to ->evict_inode probably has fixed that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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