Re: How Inactive may be much greather than cached?
Hi, On Thursday 18 October 2007 16:24, Vasily Averin wrote: Hi all, could anybody explain how inactive may be much greater than cached? stress test (http://weather.ou.edu/~apw/projects/stress/) that writes into removed files in cycle puts the node to the following state: MemTotal: 16401648 kB MemFree: 636644 kB Buffers: 1122556 kB Cached: 362880 kB SwapCached: 700 kB Active: 1604180 kB Inactive: 13609828 kB At the first glance memory should be freed on file closing, nobody refers to file and ext3_delete_inode() truncates inode. We can see that memory is go away from cached, however could somebody explain why it become invalid instead be freed? Who holds the references to these pages? Buffers, swap cache, and anonymous. - To unsubscribe from this list: send the line unsubscribe linux-ext4 in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How Inactive may be much greather than cached?
Nick Piggin wrote: Hi, On Thursday 18 October 2007 16:24, Vasily Averin wrote: Hi all, could anybody explain how inactive may be much greater than cached? stress test (http://weather.ou.edu/~apw/projects/stress/) that writes into removed files in cycle puts the node to the following state: MemTotal: 16401648 kB MemFree: 636644 kB Buffers: 1122556 kB Cached: 362880 kB SwapCached: 700 kB Active: 1604180 kB Inactive: 13609828 kB At the first glance memory should be freed on file closing, nobody refers to file and ext3_delete_inode() truncates inode. We can see that memory is go away from cached, however could somebody explain why it become invalid instead be freed? Who holds the references to these pages? Buffers, swap cache, and anonymous. But buffers and swap cache are low (1.1 Gb and 700kB in this example) and anonymous should go away when process finished. - To unsubscribe from this list: send the line unsubscribe linux-ext4 in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How Inactive may be much greather than cached?
On Thursday 18 October 2007 17:14, Vasily Averin wrote: Nick Piggin wrote: Hi, On Thursday 18 October 2007 16:24, Vasily Averin wrote: Hi all, could anybody explain how inactive may be much greater than cached? stress test (http://weather.ou.edu/~apw/projects/stress/) that writes into removed files in cycle puts the node to the following state: MemTotal: 16401648 kB MemFree:636644 kB Buffers: 1122556 kB Cached: 362880 kB SwapCached:700 kB Active:1604180 kB Inactive: 13609828 kB At the first glance memory should be freed on file closing, nobody refers to file and ext3_delete_inode() truncates inode. We can see that memory is go away from cached, however could somebody explain why it become invalid instead be freed? Who holds the references to these pages? Buffers, swap cache, and anonymous. But buffers and swap cache are low (1.1 Gb and 700kB in this example) and anonymous should go away when process finished. Ah, I didn't see it was an order of magnitude out. Some filesystems, including I believe, ext3 with data=ordered, can leave orphaned pages around after they have been truncated out of the pagecache. These pages get left on the LRU and vmscan reclaims them pretty easily. Try ext3 data=writeback, or even ext2. - To unsubscribe from this list: send the line unsubscribe linux-ext4 in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How Inactive may be much greather than cached?
Nick Piggin wrote: Some filesystems, including I believe, ext3 with data=ordered, can leave orphaned pages around after they have been truncated out of the pagecache. These pages get left on the LRU and vmscan reclaims them pretty easily. Try ext3 data=writeback, or even ext2. thanks, data=writeback helps. Resume: ext3 with data=ordered gets bh with data and moves it to journal transaction. If transaction handled immediately, ext3 frees bh on this page, and then frees this page. However if journal delays processing of this transaction, ext3 cannot free bh that is still busy. Later jbd layer decrements bh counter but it makes nothing with data page that is not freed and stays inactive. - To unsubscribe from this list: send the line unsubscribe linux-ext4 in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: How Inactive may be much greather than cached?
On Thu, 18 Oct 2007 17:27:00 +1000 Nick Piggin [EMAIL PROTECTED] wrote: Some filesystems, including I believe, ext3 with data=ordered, can leave orphaned pages around after they have been truncated out of the pagecache. These pages get left on the LRU and vmscan reclaims them pretty easily. How can the VM recognize those pages? Are they part of the buffer cache, part of the page cache, or different? I think it would make sense to at least try to rotate those pages to the end of the LRU so kswapd can get rid of them quickly. -- Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. - Brian W. Kernighan - To unsubscribe from this list: send the line unsubscribe linux-ext4 in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
