* [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets
@ 2022-04-06 20:33 Pavel Begunkov
2022-04-06 22:41 ` Jens Axboe
2022-04-07 14:10 ` Pavel Begunkov
0 siblings, 2 replies; 3+ messages in thread
From: Pavel Begunkov @ 2022-04-06 20:33 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe, asml.silence
io_uring deals with file reference loops by registering all fixed files
in the SCM/GC infrastrucure. However, only a small subset of all file
types can keep long-term references to other files and those that don't
are not interesting for the garbage collector as they can't be in a
reference loop. They neither can be directly recycled by GC nor affect
loop searching.
Let's skip io_uring SCM accounting for loop-less files, i.e. all but
af_unix sockets, quite imroving fixed file updates performance and
greatly helpnig with memory footprint.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 38 insertions(+), 13 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index b4c85d85f88d..be178694e8db 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1211,6 +1211,18 @@ struct sock *io_uring_get_socket(struct file *file)
}
EXPORT_SYMBOL(io_uring_get_socket);
+#if defined(CONFIG_UNIX)
+static inline bool io_file_need_scm(struct file *filp)
+{
+ return !!unix_get_socket(filp);
+}
+#else
+static inline bool io_file_need_scm(struct file *filp)
+{
+ return 0;
+}
+#endif
+
static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
{
if (!*locked) {
@@ -8424,6 +8436,17 @@ static void io_free_file_tables(struct io_file_table *table)
static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
{
+ int i;
+
+ for (i = 0; i < ctx->nr_user_files; i++) {
+ struct file *file = io_file_from_index(ctx, i);
+
+ if (!file || io_file_need_scm(file))
+ continue;
+ io_fixed_file_slot(&ctx->file_table, i)->file_ptr = 0;
+ fput(file);
+ }
+
#if defined(CONFIG_UNIX)
if (ctx->ring_sock) {
struct sock *sock = ctx->ring_sock->sk;
@@ -8432,16 +8455,6 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
kfree_skb(skb);
}
-#else
- int i;
-
- for (i = 0; i < ctx->nr_user_files; i++) {
- struct file *file;
-
- file = io_file_from_index(ctx, i);
- if (file)
- fput(file);
- }
#endif
io_free_file_tables(&ctx->file_table);
io_rsrc_data_free(ctx->file_data);
@@ -8590,7 +8603,9 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
/*
* Ensure the UNIX gc is aware of our file set, so we are certain that
* the io_uring can be safely unregistered on process exit, even if we have
- * loops in the file referencing.
+ * loops in the file referencing. We account only files that can hold other
+ * files because otherwise they can't form a loop and so are not interesting
+ * for GC.
*/
static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
{
@@ -8616,8 +8631,9 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
for (i = 0; i < nr; i++) {
struct file *file = io_file_from_index(ctx, i + offset);
- if (!file)
+ if (!file || !io_file_need_scm(file))
continue;
+
fpl->fp[nr_files] = get_file(file);
unix_inflight(fpl->user, fpl->fp[nr_files]);
nr_files++;
@@ -8634,7 +8650,7 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
for (i = 0; i < nr; i++) {
struct file *file = io_file_from_index(ctx, i + offset);
- if (file)
+ if (file && io_file_need_scm(file))
fput(file);
}
} else {
@@ -8676,6 +8692,7 @@ static int io_sqe_files_scm(struct io_ring_ctx *ctx)
if (file)
fput(file);
+ io_fixed_file_slot(&ctx->file_table, total)->file_ptr = 0;
total++;
}
@@ -8697,6 +8714,11 @@ static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
struct sk_buff *skb;
int i;
+ if (!io_file_need_scm(file)) {
+ fput(file);
+ return;
+ }
+
__skb_queue_head_init(&list);
/*
@@ -8889,6 +8911,9 @@ static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file,
struct sk_buff_head *head = &sock->sk_receive_queue;
struct sk_buff *skb;
+ if (!io_file_need_scm(file))
+ return 0;
+
/*
* See if we can merge this file into an existing skb SCM_RIGHTS
* file set. If there's no room, fall back to allocating a new skb
--
2.35.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets
2022-04-06 20:33 [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets Pavel Begunkov
@ 2022-04-06 22:41 ` Jens Axboe
2022-04-07 14:10 ` Pavel Begunkov
1 sibling, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2022-04-06 22:41 UTC (permalink / raw)
To: io-uring, asml.silence
On Wed, 6 Apr 2022 21:33:56 +0100, Pavel Begunkov wrote:
> io_uring deals with file reference loops by registering all fixed files
> in the SCM/GC infrastrucure. However, only a small subset of all file
> types can keep long-term references to other files and those that don't
> are not interesting for the garbage collector as they can't be in a
> reference loop. They neither can be directly recycled by GC nor affect
> loop searching.
>
> [...]
Applied, thanks!
[1/1] io_uring: don't scm-account for non af_unix sockets
commit: 181440ea22d834719489d2a33289f2834a333687
Best regards,
--
Jens Axboe
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets
2022-04-06 20:33 [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets Pavel Begunkov
2022-04-06 22:41 ` Jens Axboe
@ 2022-04-07 14:10 ` Pavel Begunkov
1 sibling, 0 replies; 3+ messages in thread
From: Pavel Begunkov @ 2022-04-07 14:10 UTC (permalink / raw)
To: io-uring; +Cc: Jens Axboe
On 4/6/22 21:33, Pavel Begunkov wrote:
> io_uring deals with file reference loops by registering all fixed files
> in the SCM/GC infrastrucure. However, only a small subset of all file
> types can keep long-term references to other files and those that don't
> are not interesting for the garbage collector as they can't be in a
> reference loop. They neither can be directly recycled by GC nor affect
> loop searching.
>
> Let's skip io_uring SCM accounting for loop-less files, i.e. all but
> af_unix sockets, quite imroving fixed file updates performance and
> greatly helpnig with memory footprint.
Just to throw some numbers, simple loop with fixed file updates
in batches of 32 showed 2-3x performance improvement
(~400K-500K updates/s -> ~1.2M).
> Signed-off-by: Pavel Begunkov <[email protected]>
> ---
> fs/io_uring.c | 51 ++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 38 insertions(+), 13 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index b4c85d85f88d..be178694e8db 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -1211,6 +1211,18 @@ struct sock *io_uring_get_socket(struct file *file)
> }
> EXPORT_SYMBOL(io_uring_get_socket);
>
> +#if defined(CONFIG_UNIX)
> +static inline bool io_file_need_scm(struct file *filp)
> +{
> + return !!unix_get_socket(filp);
> +}
> +#else
> +static inline bool io_file_need_scm(struct file *filp)
> +{
> + return 0;
> +}
> +#endif
> +
> static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
> {
> if (!*locked) {
> @@ -8424,6 +8436,17 @@ static void io_free_file_tables(struct io_file_table *table)
>
> static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
> {
> + int i;
> +
> + for (i = 0; i < ctx->nr_user_files; i++) {
> + struct file *file = io_file_from_index(ctx, i);
> +
> + if (!file || io_file_need_scm(file))
> + continue;
> + io_fixed_file_slot(&ctx->file_table, i)->file_ptr = 0;
> + fput(file);
> + }
> +
> #if defined(CONFIG_UNIX)
> if (ctx->ring_sock) {
> struct sock *sock = ctx->ring_sock->sk;
> @@ -8432,16 +8455,6 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
> while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
> kfree_skb(skb);
> }
> -#else
> - int i;
> -
> - for (i = 0; i < ctx->nr_user_files; i++) {
> - struct file *file;
> -
> - file = io_file_from_index(ctx, i);
> - if (file)
> - fput(file);
> - }
> #endif
> io_free_file_tables(&ctx->file_table);
> io_rsrc_data_free(ctx->file_data);
> @@ -8590,7 +8603,9 @@ static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
> /*
> * Ensure the UNIX gc is aware of our file set, so we are certain that
> * the io_uring can be safely unregistered on process exit, even if we have
> - * loops in the file referencing.
> + * loops in the file referencing. We account only files that can hold other
> + * files because otherwise they can't form a loop and so are not interesting
> + * for GC.
> */
> static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
> {
> @@ -8616,8 +8631,9 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
> for (i = 0; i < nr; i++) {
> struct file *file = io_file_from_index(ctx, i + offset);
>
> - if (!file)
> + if (!file || !io_file_need_scm(file))
> continue;
> +
> fpl->fp[nr_files] = get_file(file);
> unix_inflight(fpl->user, fpl->fp[nr_files]);
> nr_files++;
> @@ -8634,7 +8650,7 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
> for (i = 0; i < nr; i++) {
> struct file *file = io_file_from_index(ctx, i + offset);
>
> - if (file)
> + if (file && io_file_need_scm(file))
> fput(file);
> }
> } else {
> @@ -8676,6 +8692,7 @@ static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>
> if (file)
> fput(file);
> + io_fixed_file_slot(&ctx->file_table, total)->file_ptr = 0;
> total++;
> }
>
> @@ -8697,6 +8714,11 @@ static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
> struct sk_buff *skb;
> int i;
>
> + if (!io_file_need_scm(file)) {
> + fput(file);
> + return;
> + }
> +
> __skb_queue_head_init(&list);
>
> /*
> @@ -8889,6 +8911,9 @@ static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file,
> struct sk_buff_head *head = &sock->sk_receive_queue;
> struct sk_buff *skb;
>
> + if (!io_file_need_scm(file))
> + return 0;
> +
> /*
> * See if we can merge this file into an existing skb SCM_RIGHTS
> * file set. If there's no room, fall back to allocating a new skb
--
Pavel Begunkov
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-04-06 20:33 [PATCH 1/1] io_uring: don't scm-account for non af_unix sockets Pavel Begunkov
2022-04-06 22:41 ` Jens Axboe
2022-04-07 14:10 ` Pavel Begunkov
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