lkml.org 
[lkml]   [2003]   [Oct]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH][2.6-mm] Avoid flushing AIO workqueue on cancel/exit
When streaming AIO requests are in progress on multiple
io context's, flushing the AIO workqueue on i/o cancellation
or process exit could potentially end up waiting for a
long time as fresh requests from other active ioctx's keep
getting queued up. I haven't run into this in practice,
but it looks like a problem.

Instead, this patch increments the ioctx reference count
before queueing up a retry, ensuring that the ioctx
doesn't go away until the workqueue handler is done with
processing the ioctx and releases its reference to it.
Note: This does mean that exit_mmap can happen before the
last reference to the ioctx is gone, but only after all
iocbs have completed using the caller's mm.

Regards
Suparna

--
Suparna Bhattacharya (suparna@in.ibm.com)
Linux Technology Center
IBM Software Labs, India

diffstat aio-undo-flushworkqueue.patch
aio.c | 28 ++++++++++++----------------
1 files changed, 12 insertions(+), 16 deletions(-)
diff -urp linux-2.6.0-test6-mm4/fs/aio.c 260t6mm4/fs/aio.c
--- linux-2.6.0-test6-mm4/fs/aio.c Tue Oct 21 19:20:50 2003
+++ 260t6mm4/fs/aio.c Tue Oct 21 19:09:26 2003
@@ -63,6 +63,12 @@ LIST_HEAD(fput_head);

static void aio_kick_handler(void *);

+static inline void queue_ctx_work(struct kioctx *ctx)
+{
+ get_ioctx(ctx);
+ queue_work(aio_wq, &ctx->wq);
+}
+
/* aio_setup
* Creates the slab caches used by the aio routines, panic on
* failure as this is done early during the boot sequence.
@@ -349,15 +355,9 @@ void exit_aio(struct mm_struct *mm)
aio_cancel_all(ctx);

wait_for_all_aios(ctx);
- /*
- * this is an overkill, but ensures we don't leave
- * the ctx on the aio_wq
- */
- flush_workqueue(aio_wq);

if (1 != atomic_read(&ctx->users))
- printk(KERN_DEBUG
- "exit_aio:ioctx still alive: %d %d %d\n",
+ pr_debug("exit_aio:ioctx still alive: %d %d %d\n",
atomic_read(&ctx->users), ctx->dead,
ctx->reqs_active);
put_ioctx(ctx);
@@ -807,7 +812,7 @@ static inline void aio_run_iocbs(struct
requeue = __aio_run_iocbs(ctx);
spin_unlock_irq(&ctx->ctx_lock);
if (requeue)
- queue_work(aio_wq, &ctx->wq);
+ queue_ctx_work(ctx);
}

/*
@@ -833,7 +838,8 @@ static void aio_kick_handler(void *data)
spin_unlock_irq(&ctx->ctx_lock);
set_fs(oldfs);
if (requeue)
- queue_work(aio_wq, &ctx->wq);
+ queue_ctx_work(ctx);
+ put_ioctx(ctx);
}


@@ -854,7 +860,7 @@ void queue_kicked_iocb(struct kiocb *ioc
run = __queue_kicked_iocb(iocb);
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
if (run) {
- queue_work(aio_wq, &ctx->wq);
+ queue_ctx_work(ctx);
aio_wakeups++;
}
}
@@ -1201,11 +1207,6 @@ static void io_destroy(struct kioctx *io

aio_cancel_all(ioctx);
wait_for_all_aios(ioctx);
- /*
- * this is an overkill, but ensures we don't leave
- * the ctx on the aio_wq
- */
- flush_workqueue(aio_wq);
put_ioctx(ioctx); /* once for the lookup */
}

@@ -1524,7 +1525,7 @@ int io_submit_one(struct kioctx *ctx, st
spin_unlock_irq(&ctx->ctx_lock);

if (-EIOCBRETRY == ret)
- queue_work(aio_wq, &ctx->wq);
+ queue_ctx_work(ctx);

if (need_putctx)
put_ioctx(ctx);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 13:58    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site