On 1/23/25 7:27 AM, Pavel Begunkov wrote:
> On 1/23/25 14:21, Jens Axboe wrote:
>> init_once is called when an object doesn't come from the cache, and
>> hence needs initial clearing of certain members. While the whole
>> struct could get cleared by memset() in that case, a few of the cache
>> members are large enough that this may cause unnecessary overhead if
>> the caches used aren't large enough to satisfy the workload. For those
>> cases, some churn of kmalloc+kfree is to be expected.
>>
>> Ensure that the 3 users that need clearing put the members they need
>> cleared at the start of the struct, and place an empty placeholder
>> 'init' member so that the cache initialization knows how much to
>> clear.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> include/linux/io_uring/cmd.h | 3 ++-
>> include/linux/io_uring_types.h | 3 ++-
>> io_uring/alloc_cache.h | 30 +++++++++++++++++++++---------
>> io_uring/futex.c | 4 ++--
>> io_uring/io_uring.c | 13 ++++++++-----
>> io_uring/io_uring.h | 5 ++---
>> io_uring/net.c | 11 +----------
>> io_uring/net.h | 7 +++++--
>> io_uring/poll.c | 2 +-
>> io_uring/rw.c | 10 +---------
>> io_uring/rw.h | 5 ++++-
>> io_uring/uring_cmd.c | 10 +---------
>> 12 files changed, 50 insertions(+), 53 deletions(-)
>>
>> diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
>> index a3ce553413de..8d7746d9fd23 100644
>> --- a/include/linux/io_uring/cmd.h
>> +++ b/include/linux/io_uring/cmd.h
>> @@ -19,8 +19,9 @@ struct io_uring_cmd {
>> };
>> struct io_uring_cmd_data {
>> - struct io_uring_sqe sqes[2];
>> void *op_data;
>> + int init[0];
>
> What do you think about using struct_group instead?
That's a good idea, better than the magic empty variable. I'll make that
change for v2, thanks!
--
Jens Axboe
