On 8/16/25 12:16 AM, Joanne Koong wrote:
> On Fri, Aug 15, 2025 at 4:01 AM Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx> wrote:
>>
>>
>>
>> On 8/12/25 4:40 AM, Joanne Koong wrote:
>>> Large folios are only enabled if the writeback cache isn't on.
>>> (Strictlimiting needs to be turned off if the writeback cache is used in
>>> conjunction with large folios, else this tanks performance.)
>>>
>>> Benchmarks showed noticeable improvements for writes (both sequential
>>> and random). There were no performance differences seen for random reads
>>> or direct IO. For sequential reads, there was no performance difference
>>> seen for the first read (which populates the page cache) but subsequent
>>> sequential reads showed a huge speedup.
>>>
>>> Benchmarks were run using fio on the passthrough_hp fuse server:
>>> ~/libfuse/build/example/passthrough_hp ~/libfuse ~/fuse_mnt --nopassthrough --nocache
>>>
>>> run fio in ~/fuse_mnt:
>>> fio --name=test --ioengine=sync --rw=write --bs=1M --size=5G --numjobs=2 --ramp_time=30 --group_reporting=1
>>>
>>> Results (tested on bs=256K, 1M, 5M) showed roughly a 15-20% increase in
>>> write throughput and for sequential reads after the page cache has
>>> already been populated, there was a ~800% speedup seen.
>>>
>>> Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
>>> ---
>>> fs/fuse/file.c | 18 ++++++++++++++++--
>>> 1 file changed, 16 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
>>> index adc4aa6810f5..2e7aae294c9e 100644
>>> --- a/fs/fuse/file.c
>>> +++ b/fs/fuse/file.c
>>> @@ -1167,9 +1167,10 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
>>> pgoff_t index = pos >> PAGE_SHIFT;
>>> unsigned int bytes;
>>> unsigned int folio_offset;
>>> + fgf_t fgp = FGP_WRITEBEGIN | fgf_set_order(num);
>>>
>>> again:
>>> - folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
>>> + folio = __filemap_get_folio(mapping, index, fgp,
>>> mapping_gfp_mask(mapping));
>>> if (IS_ERR(folio)) {
>>> err = PTR_ERR(folio);
>>> @@ -3155,11 +3156,24 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags)
>>> {
>>> struct fuse_inode *fi = get_fuse_inode(inode);
>>> struct fuse_conn *fc = get_fuse_conn(inode);
>>> + unsigned int max_pages, max_order;
>>>
>>> inode->i_fop = &fuse_file_operations;
>>> inode->i_data.a_ops = &fuse_file_aops;
>>> - if (fc->writeback_cache)
>>> + if (fc->writeback_cache) {
>>> mapping_set_writeback_may_deadlock_on_reclaim(&inode->i_data);
>>> + } else {
>>> + /*
>>> + * Large folios are only enabled if the writeback cache isn't on.
>>> + * If the writeback cache is on, large folios should only be
>>> + * enabled in conjunction with strictlimiting turned off, else
>>> + * performance tanks.
>>> + */
>>> + max_pages = min(min(fc->max_write, fc->max_read) >> PAGE_SHIFT,
>>> + fc->max_pages);
>>> + max_order = ilog2(max_pages);
>>> + mapping_set_folio_order_range(inode->i_mapping, 0, max_order);
>>> + }
>>
>> JFYI fc->max_read shall also be honored when calculating max_order,
>> otherwise the following warning in fuse_readahead() may be triggered.
>>
> Hi Jingbo,
>
> I think fc->max_read gets honored in the "min(fc->max_write,
> fc->max_read)" part of the max_pages calculation above.
>
Opps, yeah. My fault, sorry for the noise.
--
Thanks,
Jingbo
