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Date: Mon, 21 Jan 2013 11:18:32 +0900
From: Namjae Jeon <linkinjeon@...il.com>
To: Cong Ding <dinggnu@...il.com>
Cc: jack@...e.cz, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
Namjae Jeon <namjae.jeon@...sung.com>,
Ashish Sangwan <a.sangwan@...sung.com>,
Bonggil Bak <bgbak@...sung.com>
Subject: Re: [PATCH] udf: add extent cache support in case of file reading
2013/1/19, Cong Ding <dinggnu@...il.com>:
> On Sat, Jan 19, 2013 at 11:17:14AM +0900, Namjae Jeon wrote:
>> From: Namjae Jeon <namjae.jeon@...sung.com>
>>
>> This patch implements extent caching in case of file reading.
>> While reading a file, currently, UDF reads metadata serially
>> which takes a lot of time depending on the number of extents present
>> in the file. Caching last accessd extent improves metadata read time.
>> Instead of reading file metadata from start, now we read from
>> the cached extent.
>>
>> This patch considerably improves the time spent by CPU in kernel mode.
>> For example, while reading a 10.9 GB file using dd:
>> Time before applying patch:
>> 11677022208 bytes (10.9GB) copied, 1529.748921 seconds, 7.3MB/s
>> real 25m 29.85s
>> user 0m 12.41s
>> sys 15m 34.75s
>>
>> Time after applying patch:
>> 11677022208 bytes (10.9GB) copied, 1469.338231 seconds, 7.6MB/s
>> real 24m 29.44s
>> user 0m 15.73s
>> sys 3m 27.61s
> did you have any test on lots of small files?
Hi. Cong.
I created 2048 files of each 512KB size for testing performance
drpping by extent cache feature.
Used this script to read every file:
index=0
while [ $index != 2048 ]
do
dd if=file.$index of=/dev/zero 1> /dev/null 2>/dev/null
index=$(($index + 1))
done
Performance without patch:
VDLinux#> echo 3 > /proc/sys/vm/drop_caches
VDLinux#> time ./script2.sh
real 0m 55.13s
user 0m 1.40s
sys 0m 25.17s
Performace with patch =>
VDLinux#> time ./script2.sh
real 0m 53.70s
user 0m 1.60s
sys 0m 25.11s
I can not find any performance dropping with extent cache patch.
Thanks.
>
> - cong
>>
>> Signed-off-by: Namjae Jeon <namjae.jeon@...sung.com>
>> Signed-off-by: Ashish Sangwan <a.sangwan@...sung.com>
>> Signed-off-by: Bonggil Bak <bgbak@...sung.com>
>> ---
>> fs/udf/ialloc.c | 4 +++
>> fs/udf/inode.c | 79
>> +++++++++++++++++++++++++++++++++++++++++++++++++-----
>> fs/udf/udf_i.h | 16 +++++++++++
>> fs/udf/udfdecl.h | 10 +++----
>> 4 files changed, 98 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/udf/ialloc.c b/fs/udf/ialloc.c
>> index 7e5aae4..0cb208e 100644
>> --- a/fs/udf/ialloc.c
>> +++ b/fs/udf/ialloc.c
>> @@ -117,6 +117,10 @@ struct inode *udf_new_inode(struct inode *dir,
>> umode_t mode, int *err)
>> iinfo->i_lenAlloc = 0;
>> iinfo->i_use = 0;
>> iinfo->i_checkpoint = 1;
>> + memset(&iinfo->cached_extent, 0, sizeof(struct udf_ext_cache));
>> + spin_lock_init(&(iinfo->i_extent_cache_lock));
>> + /* Mark extent cache as invalid for now */
>> + iinfo->cached_extent.lstart = -1;
>> if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_AD_IN_ICB))
>> iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;
>> else if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))
>> diff --git a/fs/udf/inode.c b/fs/udf/inode.c
>> index e78ef48..86e0469 100644
>> --- a/fs/udf/inode.c
>> +++ b/fs/udf/inode.c
>> @@ -91,6 +91,7 @@ void udf_evict_inode(struct inode *inode)
>> }
>> kfree(iinfo->i_ext.i_data);
>> iinfo->i_ext.i_data = NULL;
>> + udf_clear_extent_cache(iinfo);
>> if (want_delete) {
>> udf_free_inode(inode);
>> }
>> @@ -106,6 +107,7 @@ static void udf_write_failed(struct address_space
>> *mapping, loff_t to)
>> truncate_pagecache(inode, to, isize);
>> if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
>> down_write(&iinfo->i_data_sem);
>> + udf_clear_extent_cache(iinfo);
>> udf_truncate_extents(inode);
>> up_write(&iinfo->i_data_sem);
>> }
>> @@ -373,7 +375,7 @@ static int udf_get_block(struct inode *inode, sector_t
>> block,
>> iinfo->i_next_alloc_goal++;
>> }
>>
>> -
>> + udf_clear_extent_cache(iinfo);
>> phys = inode_getblk(inode, block, &err, &new);
>> if (!phys)
>> goto abort;
>> @@ -1172,6 +1174,7 @@ set_size:
>> } else {
>> if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
>> down_write(&iinfo->i_data_sem);
>> + udf_clear_extent_cache(iinfo);
>> memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr + newsize,
>> 0x00, bsize - newsize -
>> udf_file_entry_alloc_offset(inode));
>> @@ -1185,6 +1188,7 @@ set_size:
>> if (err)
>> return err;
>> down_write(&iinfo->i_data_sem);
>> + udf_clear_extent_cache(iinfo);
>> truncate_setsize(inode, newsize);
>> udf_truncate_extents(inode);
>> up_write(&iinfo->i_data_sem);
>> @@ -1302,6 +1306,9 @@ static void udf_fill_inode(struct inode *inode,
>> struct buffer_head *bh)
>> iinfo->i_lenAlloc = 0;
>> iinfo->i_next_alloc_block = 0;
>> iinfo->i_next_alloc_goal = 0;
>> + memset(&iinfo->cached_extent, 0, sizeof(struct udf_ext_cache));
>> + spin_lock_init(&(iinfo->i_extent_cache_lock));
>> + iinfo->cached_extent.lstart = -1;
>> if (fe->descTag.tagIdent == cpu_to_le16(TAG_IDENT_EFE)) {
>> iinfo->i_efe = 1;
>> iinfo->i_use = 0;
>> @@ -2157,11 +2164,12 @@ int8_t inode_bmap(struct inode *inode, sector_t
>> block,
>> struct udf_inode_info *iinfo;
>>
>> iinfo = UDF_I(inode);
>> - pos->offset = 0;
>> - pos->block = iinfo->i_location;
>> - pos->bh = NULL;
>> + if (!udf_read_extent_cache(inode, bcount, &lbcount, pos)) {
>> + pos->offset = 0;
>> + pos->block = iinfo->i_location;
>> + pos->bh = NULL;
>> + }
>> *elen = 0;
>> -
>> do {
>> etype = udf_next_aext(inode, pos, eloc, elen, 1);
>> if (etype == -1) {
>> @@ -2171,7 +2179,8 @@ int8_t inode_bmap(struct inode *inode, sector_t
>> block,
>> }
>> lbcount += *elen;
>> } while (lbcount <= bcount);
>> -
>> + /* update extent cache */
>> + udf_update_extent_cache(inode, lbcount - *elen, pos, 1);
>> *offset = (bcount + *elen - lbcount) >> blocksize_bits;
>>
>> return etype;
>> @@ -2201,3 +2210,61 @@ long udf_block_map(struct inode *inode, sector_t
>> block)
>> else
>> return ret;
>> }
>> +
>> +int udf_read_extent_cache(struct inode *inode, loff_t bcount,
>> + loff_t *lbcount, struct extent_position *pos)
>> +{
>> + struct udf_inode_info *iinfo = UDF_I(inode);
>> +
>> + spin_lock(&iinfo->i_extent_cache_lock);
>> + if ((iinfo->cached_extent.lstart <= bcount) &&
>> + (iinfo->cached_extent.lstart != -1)) {
>> + /* Cache hit */
>> + *lbcount = iinfo->cached_extent.lstart;
>> + memcpy(pos, &iinfo->cached_extent.epos,
>> + sizeof(struct extent_position));
>> + spin_unlock(&iinfo->i_extent_cache_lock);
>> + return 1;
>> + } else
>> + udf_clear_extent_cache(iinfo);
>> + spin_unlock(&iinfo->i_extent_cache_lock);
>> + return 0;
>> +}
>> +
>> +void udf_update_extent_cache(struct inode *inode, loff_t estart,
>> + struct extent_position *pos, int next_epos)
>> +{
>> + struct udf_inode_info *iinfo = UDF_I(inode);
>> +
>> + spin_lock(&iinfo->i_extent_cache_lock);
>> + if (pos->bh != NULL)
>> + /* Increase ref count */
>> + get_bh(pos->bh);
>> + memcpy(&iinfo->cached_extent.epos, pos,
>> + sizeof(struct extent_position));
>> + iinfo->cached_extent.lstart = estart;
>> + if (next_epos)
>> + switch (iinfo->i_alloc_type) {
>> + case ICBTAG_FLAG_AD_SHORT:
>> + iinfo->cached_extent.epos.offset -=
>> + sizeof(struct short_ad);
>> + break;
>> + case ICBTAG_FLAG_AD_LONG:
>> + iinfo->cached_extent.epos.offset -=
>> + sizeof(struct long_ad);
>> + }
>> + spin_unlock(&iinfo->i_extent_cache_lock);
>> +}
>> +
>> +/* This function should be called after i_data_sem is
>> + * held for writing OR i_extent_cache_lock is taken.
>> + */
>> +void udf_clear_extent_cache(struct udf_inode_info *iinfo)
>> +{
>> + if (iinfo->cached_extent.lstart != -1) {
>> + brelse(iinfo->cached_extent.epos.bh);
>> + memset(&iinfo->cached_extent, 0, sizeof(struct udf_ext_cache));
>> + iinfo->cached_extent.lstart = -1;
>> + }
>> +}
>> +
>> diff --git a/fs/udf/udf_i.h b/fs/udf/udf_i.h
>> index bb8309d..b5cd8ed 100644
>> --- a/fs/udf/udf_i.h
>> +++ b/fs/udf/udf_i.h
>> @@ -1,6 +1,19 @@
>> #ifndef _UDF_I_H
>> #define _UDF_I_H
>>
>> +struct extent_position {
>> + struct buffer_head *bh;
>> + uint32_t offset;
>> + struct kernel_lb_addr block;
>> +};
>> +
>> +struct udf_ext_cache {
>> + /* Extent position */
>> + struct extent_position epos;
>> + /* Start logical offset in bytes */
>> + loff_t lstart;
>> +};
>> +
>> /*
>> * The i_data_sem and i_mutex serve for protection of allocation
>> information
>> * of a regular files and symlinks. This includes all extents belonging
>> to
>> @@ -35,6 +48,9 @@ struct udf_inode_info {
>> __u8 *i_data;
>> } i_ext;
>> struct rw_semaphore i_data_sem;
>> + struct udf_ext_cache cached_extent;
>> + /* Spinlock for protecting extent cache */
>> + spinlock_t i_extent_cache_lock;
>> struct inode vfs_inode;
>> };
>>
>> diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
>> index de038da..db4a22e 100644
>> --- a/fs/udf/udfdecl.h
>> +++ b/fs/udf/udfdecl.h
>> @@ -113,11 +113,6 @@ struct ustr {
>> uint8_t u_len;
>> };
>>
>> -struct extent_position {
>> - struct buffer_head *bh;
>> - uint32_t offset;
>> - struct kernel_lb_addr block;
>> -};
>>
>> /* super.c */
>>
>> @@ -164,6 +159,11 @@ extern int8_t udf_next_aext(struct inode *, struct
>> extent_position *,
>> struct kernel_lb_addr *, uint32_t *, int);
>> extern int8_t udf_current_aext(struct inode *, struct extent_position *,
>> struct kernel_lb_addr *, uint32_t *, int);
>> +int udf_read_extent_cache(struct inode *inode, loff_t bcount, loff_t
>> *lbcount,
>> + struct extent_position *pos);
>> +void udf_update_extent_cache(struct inode *inode, loff_t estart,
>> + struct extent_position *pos, int next_epos);
>> +void udf_clear_extent_cache(struct udf_inode_info *iinfo);
>>
>> /* misc.c */
>> extern struct buffer_head *udf_tgetblk(struct super_block *, int);
>> --
>> 1.7.9.5
>>
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