Hi Andrey,
In looking further at fio_libaio_event(), I am wondering if it is possible to get the errno value if one of the events have an error (i.e. if ev->res != io_u->xfer_buflen).
I see that io_u->error is set to –ev->res if ev->res is greater than io_u->xfer_buflen. But since my io_u->xfer_buflen is a large value, I am guessing that this is not the errno value that caused the error. Is that true?
Also, if ev->res is less than io_u->xfer_buflen, then io_u->resid is set to (io_u->xfer_buflen - ev->res). Does that mean that there will be another attempt to write out the io_u->resid bytes?
Again, thanks to you and the others on the fio mailing list for any guidance you can give.
Sincerely,
Scott
From: Andrey Kuzmin <andrey.v.kuzmin@xxxxxxxxx>
Date: Tuesday, March 28, 2017 at 11:22 AM
To: "Scott Forman (scforman)" <scforman@xxxxxxxxx>, "fio@xxxxxxxxxxxxxxx" <fio@xxxxxxxxxxxxxxx>
Subject: Re: How does FIO detect write errors when ioengine is libaio
On Tue, Mar 28, 2017, 21:13 Scott Forman (scforman) <scforman@xxxxxxxxx> wrote:
Hi,
I am trying to determine how fio detects write errors when the ioengine is set to libaio.
>From a code example on stack overflow, linux-kernel-aio-functionality, it appears that they can be detected by examining the events returned from io_getevents().
But I do not see any code in libaio.c that examines the events returned from io_getevents().
static struct io_u *fio_libaio_event(struct thread_data *td, int event)
{
struct libaio_data *ld = td->io_ops_data;
struct io_event *ev;
struct io_u *io_u;
ev = ld->aio_events + event;
io_u = container_of(ev->obj, struct io_u, iocb);
if (ev->res != io_u->xfer_buflen) {
if (ev->res > io_u->xfer_buflen)
io_u->error = -ev->res;
else
io_u->resid = io_u->xfer_buflen - ev->res;
} else
io_u->error = 0;
Regards,
Andrey
Can you verify that fio does check for write errors for engine libaio, and if so, where that error checking is done?
Thanks in advance!
Sincerely,
Scott Forman
--
Regards,
Andrey
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