Re: [f2fs-dev] [PATCH v2] f2fs: compress: reduce one page array alloc and free when write compressed page

[Chao Yu <chao@kernel.org>]

On 2021/11/10 10:34, 常凤楠 wrote:
> 
> 
>> -----Original Message-----
>> From: changfengnan@vivo.com <changfengnan@vivo.com> On Behalf Of
>> Chao Yu
>> Sent: Tuesday, November 9, 2021 10:11 PM
>> To: 常凤楠 <changfengnan@vivo.com>; jaegeuk@kernel.org
>> Cc: linux-f2fs-devel@lists.sourceforge.net
>> Subject: Re: [PATCH v2] f2fs: compress: reduce one page array alloc and
>> free when write compressed page
>>
>> On 2021/11/9 11:54, Fengnan Chang wrote:
>>> Don't alloc new page pointers array to replace old, just use old,
>>> introduce valid_nr_cpages to indicate valid number of page pointers in
>>> array, try to reduce one page array alloc and free when write compress
>> page.
>>>
>>> Signed-off-by: Fengnan Chang <changfengnan@vivo.com>
>>> ---
>>>    fs/f2fs/compress.c | 27 +++++++++------------------
>>>    fs/f2fs/data.c     |  1 +
>>>    fs/f2fs/f2fs.h     |  1 +
>>>    3 files changed, 11 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index
>>> 9b663eaf4805..28785dd78c6f 100644
>>> --- a/fs/f2fs/compress.c
>>> +++ b/fs/f2fs/compress.c
>>> @@ -153,6 +153,7 @@ void f2fs_destroy_compress_ctx(struct
>> compress_ctx *cc, bool reuse)
>>>    	cc->rpages = NULL;
>>>    	cc->nr_rpages = 0;
>>>    	cc->nr_cpages = 0;
>>> +	cc->valid_nr_cpages = 0;
>>>    	if (!reuse)
>>>    		cc->cluster_idx = NULL_CLUSTER;
>>>    }
>>> @@ -619,7 +620,6 @@ static int f2fs_compress_pages(struct
>> compress_ctx *cc)
>>>    	const struct f2fs_compress_ops *cops =
>>>    				f2fs_cops[fi->i_compress_algorithm];
>>>    	unsigned int max_len, new_nr_cpages;
>>> -	struct page **new_cpages;
>>>    	u32 chksum = 0;
>>>    	int i, ret;
>>>
>>> @@ -634,6 +634,7 @@ static int f2fs_compress_pages(struct
>> compress_ctx
>>> *cc)
>>>
>>>    	max_len = COMPRESS_HEADER_SIZE + cc->clen;
>>>    	cc->nr_cpages = DIV_ROUND_UP(max_len, PAGE_SIZE);
>>> +	cc->valid_nr_cpages = cc->nr_cpages;
>>>
>>>    	cc->cpages = page_array_alloc(cc->inode, cc->nr_cpages);
>>>    	if (!cc->cpages) {
>>> @@ -684,13 +685,6 @@ static int f2fs_compress_pages(struct
>>> compress_ctx *cc)
>>>
>>>    	new_nr_cpages = DIV_ROUND_UP(cc->clen +
>> COMPRESS_HEADER_SIZE,
>>> PAGE_SIZE);
>>>
>>> -	/* Now we're going to cut unnecessary tail pages */
>>> -	new_cpages = page_array_alloc(cc->inode, new_nr_cpages);
>>> -	if (!new_cpages) {
>>> -		ret = -ENOMEM;
>>> -		goto out_vunmap_cbuf;
>>
>> It removes last user of out_vunmap_cbuf label, so we can remove below
>> dead codes in error path as well.
>>
>> out_vunmap_cbuf:
>> 	vm_unmap_ram(cc->cbuf, cc->nr_cpages);
> 
> Not right, there still other code use this.

Oh, right. :)

Thanks,

> 
> Thanks.
>>
>>> -	}
>>> -
>>>    	/* zero out any unused part of the last page */
>>>    	memset(&cc->cbuf->cdata[cc->clen], 0,
>>>    			(new_nr_cpages * PAGE_SIZE) -
>>> @@ -701,7 +695,6 @@ static int f2fs_compress_pages(struct
>> compress_ctx
>>> *cc)
>>>
>>>    	for (i = 0; i < cc->nr_cpages; i++) {
>>>    		if (i < new_nr_cpages) {
>>> -			new_cpages[i] = cc->cpages[i];
>>>    			continue;
>>>    		}
>>
>> if (i < new_nr_cpages)
>> 	continue;
>>
>>>    		f2fs_compress_free_page(cc->cpages[i]);
>>> @@ -711,9 +704,7 @@ static int f2fs_compress_pages(struct
>> compress_ctx *cc)
>>>    	if (cops->destroy_compress_ctx)
>>>    		cops->destroy_compress_ctx(cc);
>>>
>>> -	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
>>> -	cc->cpages = new_cpages;
>>> -	cc->nr_cpages = new_nr_cpages;
>>> +	cc->valid_nr_cpages = new_nr_cpages;
>>>
>>>    	trace_f2fs_compress_pages_end(cc->inode, cc->cluster_idx,
>>>    							cc->clen, ret);
>>> @@ -1288,14 +1279,14 @@ static int
>> f2fs_write_compressed_pages(struct
>>> compress_ctx *cc,
>>>
>>>    	cic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
>>>    	cic->inode = inode;
>>> -	atomic_set(&cic->pending_pages, cc->nr_cpages);
>>> +	atomic_set(&cic->pending_pages, cc->valid_nr_cpages);
>>>    	cic->rpages = page_array_alloc(cc->inode, cc->cluster_size);
>>>    	if (!cic->rpages)
>>>    		goto out_put_cic;
>>>
>>>    	cic->nr_rpages = cc->cluster_size;
>>>
>>> -	for (i = 0; i < cc->nr_cpages; i++) {
>>> +	for (i = 0; i < cc->valid_nr_cpages; i++) {
>>>    		f2fs_set_compressed_page(cc->cpages[i], inode,
>>>    					cc->rpages[i + 1]->index, cic);
>>>    		fio.compressed_page = cc->cpages[i]; @@ -1340,7 +1331,7
>> @@ static
>>> int f2fs_write_compressed_pages(struct compress_ctx *cc,
>>>    		if (fio.compr_blocks && __is_valid_data_blkaddr(blkaddr))
>>>    			fio.compr_blocks++;
>>>
>>> -		if (i > cc->nr_cpages) {
>>> +		if (i > cc->valid_nr_cpages) {
>>>    			if (__is_valid_data_blkaddr(blkaddr)) {
>>>    				f2fs_invalidate_blocks(sbi, blkaddr);
>>>    				f2fs_update_data_blkaddr(&dn, NEW_ADDR); @@
>> -1365,8 +1356,8 @@
>>> static int f2fs_write_compressed_pages(struct compress_ctx *cc,
>>>
>>>    	if (fio.compr_blocks)
>>>    		f2fs_i_compr_blocks_update(inode, fio.compr_blocks - 1,
>> false);
>>> -	f2fs_i_compr_blocks_update(inode, cc->nr_cpages, true);
>>> -	add_compr_block_stat(inode, cc->nr_cpages);
>>> +	f2fs_i_compr_blocks_update(inode, cc->valid_nr_cpages, true);
>>> +	add_compr_block_stat(inode, cc->valid_nr_cpages);
>>>
>>>    	set_inode_flag(cc->inode, FI_APPEND_WRITE);
>>>    	if (cc->cluster_idx == 0)
>>> @@ -1404,7 +1395,7 @@ static int f2fs_write_compressed_pages(struct
>> compress_ctx *cc,
>>>    	else
>>>    		f2fs_unlock_op(sbi);
>>>    out_free:
>>> -	for (i = 0; i < cc->nr_cpages; i++) {
>>> +	for (i = 0; i < cc->valid_nr_cpages; i++) {
>>>    		if (!cc->cpages[i])
>>>    			continue;
>>
>> We can remove above cpages check?
>>
>> Thanks,
>>
>>>    		f2fs_compress_free_page(cc->cpages[i]);
>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index
>>> f4fd6c246c9a..4ddc0ba0f2c0 100644
>>> --- a/fs/f2fs/data.c
>>> +++ b/fs/f2fs/data.c
>>> @@ -2934,6 +2934,7 @@ static int f2fs_write_cache_pages(struct
>> address_space *mapping,
>>>    		.rpages = NULL,
>>>    		.nr_rpages = 0,
>>>    		.cpages = NULL,
>>> +		.valid_nr_cpages = 0,
>>>    		.rbuf = NULL,
>>>    		.cbuf = NULL,
>>>    		.rlen = PAGE_SIZE * F2FS_I(inode)->i_cluster_size, diff --git
>>> a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 039a229e11c9..acb587f054db
>>> 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -1481,6 +1481,7 @@ struct compress_ctx {
>>>    	unsigned int nr_rpages;		/* total page number in rpages
>> */
>>>    	struct page **cpages;		/* pages store compressed data in
>> cluster */
>>>    	unsigned int nr_cpages;		/* total page number in cpages
>> */
>>> +	unsigned int valid_nr_cpages;	/* valid page number in cpages */
>>>    	void *rbuf;			/* virtual mapped address on rpages */
>>>    	struct compress_data *cbuf;	/* virtual mapped address on
>> cpages */
>>>    	size_t rlen;			/* valid data length in rbuf */
>>>


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel