linux-kernel - Re: [PATCH RESEND v1 05/16] vfs: add hooks to enable hot tracking

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Message-ID: <CAEH94LhdK1gS6Z17yL6gcvxJ=kdCihO29VtonEZ4-iN2+BAksg@mail.gmail.com>
Date:	Fri, 11 Jan 2013 15:47:20 +0800
From:	Zhi Yong Wu <zwu.kernel@...il.com>
To:	dsterba@...e.cz
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	viro@...iv.linux.org.uk, david@...morbit.com,
	darrick.wong@...cle.com, andi@...stfloor.org, hch@...radead.org,
	linuxram@...ux.vnet.ibm.com, wuzhy@...ux.vnet.ibm.com
Subject: Re: [PATCH RESEND v1 05/16] vfs: add hooks to enable hot tracking

On Thu, Jan 10, 2013 at 8:52 AM, David Sterba <dsterba@...e.cz> wrote:
> On Thu, Dec 20, 2012 at 10:43:24PM +0800, zwu.kernel@...il.com wrote:
>> --- a/fs/direct-io.c
>> +++ b/fs/direct-io.c
>> @@ -37,6 +37,7 @@
>>  #include <linux/uio.h>
>>  #include <linux/atomic.h>
>>  #include <linux/prefetch.h>
>> +#include "hot_tracking.h"
>>
>>  /*
>>   * How many user pages to map in one call to get_user_pages().  This determines
>> @@ -1299,6 +1300,11 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
>>       prefetch(bdev->bd_queue);
>>       prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES);
>>
>> +     /* Hot data tracking */
>> +     hot_update_freqs(inode, offset,
>> +                     iov_length(iov, nr_segs),
>> +                     rw & WRITE);
>
> hot_update_freqs takes an 'int rw' directly, so you should pass plain
> 'rw' here and do the 'rw & WRITE' check in hot_freq_data_update itself.
OK, done.
>
>> +
>>       return do_blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
>>                                    nr_segs, get_block, end_io,
>>                                    submit_io, flags);
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -35,6 +35,7 @@
>>  #include <linux/buffer_head.h> /* __set_page_dirty_buffers */
>>  #include <linux/pagevec.h>
>>  #include <linux/timer.h>
>> +#include <linux/hot_tracking.h>
>>  #include <trace/events/writeback.h>
>>
>>  /*
>> @@ -1902,13 +1903,24 @@ EXPORT_SYMBOL(generic_writepages);
>>  int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
>>  {
>>       int ret;
>> +     loff_t start = 0;
>> +     size_t count = 0;
>>
>>       if (wbc->nr_to_write <= 0)
>>               return 0;
>> +
>> +     start = mapping->writeback_index << PAGE_CACHE_SHIFT;
>> +     count = wbc->nr_to_write;
>> +
>>       if (mapping->a_ops->writepages)
>>               ret = mapping->a_ops->writepages(mapping, wbc);
>>       else
>>               ret = generic_writepages(mapping, wbc);
>> +
>> +     /* Hot data tracking */
>> +     hot_update_freqs(mapping->host, start,
>> +                     (count - wbc->nr_to_write) * PAGE_CACHE_SIZE, 1);
>
> I think the frequencies should not be updated in case of error returned
> from writepages.
OK, Done.
>
>> +
>>       return ret;
>>  }
>>
>> --- a/mm/readahead.c
>> +++ b/mm/readahead.c
>> @@ -138,6 +139,12 @@ static int read_pages(struct address_space *mapping, struct file *filp,
>>  out:
>>       blk_finish_plug(&plug);
>>
>> +     /* Hot data tracking */
>> +     hot_update_freqs(mapping->host,
>> +             (loff_t)(list_entry(pages->prev, struct page, lru)->index)
>> +                     << PAGE_CACHE_SHIFT,
>> +             (size_t)nr_pages * PAGE_CACHE_SIZE, 0);
>
> same comment here
Ditto. thanks.
>
>> +
>>       return ret;
>>  }
>
>
> david



-- 
Regards,

Zhi Yong Wu
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