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io_uring: use kvmalloc for fixed files

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Instead of hand-coded two-level tables for registered files, allocate
them with kvmalloc(). In many cases small enough tables are enough, and
so can be kmalloc()'ed removing an extra memory load and a bunch of bit
logic instructions from the hot path. If the table is larger, we trade
off all the pros with a TLB-assisted memory lookup.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/280421d3b48775dabab773006bb5588c7b2dabc0.1628471125.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-08-09 13:04:01 +01:00 committed by Jens Axboe
parent 5fd4617840
commit 042b0d85ea
1 changed files with 10 additions and 23 deletions
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33
fs/io_uring.c
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@ -92,13 +92,8 @@
#define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES)
#define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
/*
* Shift of 9 is 512 entries, or exactly one page on 64-bit archs
*/
#define IORING_FILE_TABLE_SHIFT 9
#define IORING_MAX_FILES_TABLE (1U << IORING_FILE_TABLE_SHIFT)
#define IORING_FILE_TABLE_MASK (IORING_MAX_FILES_TABLE - 1)
#define IORING_MAX_FIXED_FILES (64 * IORING_MAX_FILES_TABLE)
/* 512 entries per page on 64-bit archs, 64 pages max */
#define IORING_MAX_FIXED_FILES (1U << 15)
#define IORING_MAX_RESTRICTIONS (IORING_RESTRICTION_LAST + \
IORING_REGISTER_LAST + IORING_OP_LAST)
@ -235,8 +230,7 @@ struct io_rsrc_put {
};
struct io_file_table {
/* two level table */
struct io_fixed_file **files;
struct io_fixed_file *files;
};
struct io_rsrc_node {
@ -6333,12 +6327,9 @@ static void io_wq_submit_work(struct io_wq_work *work)
#define FFS_MASK ~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
static inline struct io_fixed_file *io_fixed_file_slot(struct io_file_table *table,
unsigned i)
unsigned i)
{
struct io_fixed_file *table_l2;
table_l2 = table->files[i >> IORING_FILE_TABLE_SHIFT];
return &table_l2[i & IORING_FILE_TABLE_MASK];
return &table->files[i];
}
static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
@ -7276,17 +7267,13 @@ fail:
static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
{
size_t size = nr_files * sizeof(struct io_fixed_file);
table->files = (struct io_fixed_file **)io_alloc_page_table(size);
table->files = kvcalloc(nr_files, sizeof(table->files[0]), GFP_KERNEL);
return !!table->files;
}
static void io_free_file_tables(struct io_file_table *table, unsigned nr_files)
static void io_free_file_tables(struct io_file_table *table)
{
size_t size = nr_files * sizeof(struct io_fixed_file);
io_free_page_table((void **)table->files, size);
kvfree(table->files);
table->files = NULL;
}
@ -7311,7 +7298,7 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
fput(file);
}
#endif
io_free_file_tables(&ctx->file_table, ctx->nr_user_files);
io_free_file_tables(&ctx->file_table);
io_rsrc_data_free(ctx->file_data);
ctx->file_data = NULL;
ctx->nr_user_files = 0;
@ -7779,7 +7766,7 @@ out_fput:
if (file)
fput(file);
}
io_free_file_tables(&ctx->file_table, nr_args);
io_free_file_tables(&ctx->file_table);
ctx->nr_user_files = 0;
out_free:
io_rsrc_data_free(ctx->file_data);