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Re: [Qemu-devel] [V7 1/1] fsdev: add IO throttle support to fsdev device


From: Pradeep Jagadeesh
Subject: Re: [Qemu-devel] [V7 1/1] fsdev: add IO throttle support to fsdev devices
Date: Tue, 25 Oct 2016 11:39:15 +0200
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0

On 10/24/2016 11:28 PM, Greg Kurz wrote:
Re-post (I had hit the send button by error :)

On Sat, 22 Oct 2016 11:07:22 -0400
Pradeep Jagadeesh <address@hidden> wrote:

Signed-off-by: Pradeep Jagadeesh <address@hidden>
---

Hi Pradeep,

I see that Berto already did a thorough review for this patch and I agree for
all the suggestions he made.

I have some more to add. First: this patch doesn't apply, please rebase.
Hi Greg,

Thanks for having a look at the patch. I will incorporate the comments and send the patch early next week as I am out of office till then.

-Pradeep


More remarks below.

 fsdev/Makefile.objs         |   1 +
 fsdev/file-op-9p.h          |   3 +
 fsdev/qemu-fsdev-opts.c     |  76 +++++++++++++++++++++++
 fsdev/qemu-fsdev-throttle.c | 147 ++++++++++++++++++++++++++++++++++++++++++++
 fsdev/qemu-fsdev-throttle.h |  37 +++++++++++
 hw/9pfs/9p-local.c          |   9 ++-
 hw/9pfs/9p.c                |   6 ++
 hw/9pfs/cofile.c            |   5 ++
 8 files changed, 282 insertions(+), 2 deletions(-)
 create mode 100644 fsdev/qemu-fsdev-throttle.c
 create mode 100644 fsdev/qemu-fsdev-throttle.h

This adds the support for the 9p-local driver.
For now this functionality can be enabled only through qemu cli options.
QMP interface and support to other drivers need further extensions.
To make it simple for other drivers, the throttle code has been put in
separate files.


The above lines are the changelog for the patch. We want this to be displayed
when running 'git log'. For this to happen, please move these lines above your
SoB tag.

Only the vN -> vN+1 changes are not relevant (we don't need to record all the
intermediate reviews in git) and should stay here.

v1 -> v2:

-Fixed FsContext redeclaration issue
-Removed couple of function declarations from 9p-throttle.h
-Fixed some of the .help messages

v2 -> v3:

-Addressed follwing comments by Claudio Fontana
 -Removed redundant memset calls in fsdev_throttle_configure_iolimits function
 -Checking throttle structure validity before initializing other structures
  in fsdev_throttle_configure_iolimits

-Addressed following comments by Greg Kurz
 -Moved the code from 9pfs directory to fsdev directory, because the throttling
  is for the fsdev devices.Renamed the files and functions to fsdev_ from 9pfs_
 -Renamed throttling cli options to throttling.*, as in QMP cli options
 -Removed some of the unwanted .h files from qemu-fsdev-throttle.[ch]
 -Using throttle_enabled() function to set the thottle enabled flag for fsdev.

v3 -> v4:

-Addressed following comments by Alberto Garcia
 -Removed the unwanted locking and other data structures in 
qemu-fsdev-throttle.[ch]

-Addressed following comments by Greg Kurz
 -Removed fsdev_iolimitsenable/disable functions, instead using 
throttle_enabled function

v4 -> V5:
 -Fixed the issue with the larger block size accounting.
 (i.e, when the 9pfs mounted using msize=xxx option)

V5 -> V6:
-Addressed the comments by Alberto Garcia
 -Removed the fsdev_throttle_timer_cb()
 -Simplified the  fsdev_throttle_schedule_next_request() as suggested

V6 -> V7:
-Addressed the comments by Alberto Garcia
 -changed the  fsdev_throttle_schedule_next_request() as suggested


diff --git a/fsdev/Makefile.objs b/fsdev/Makefile.objs
index 1b120a4..2c6da2d 100644
--- a/fsdev/Makefile.objs
+++ b/fsdev/Makefile.objs
@@ -7,6 +7,7 @@ common-obj-y = qemu-fsdev-dummy.o
 endif
 common-obj-y += qemu-fsdev-opts.o

+common-obj-y += qemu-fsdev-throttle.o
 # Toplevel always builds this; targets without virtio will put it in
 # common-obj-y
 common-obj-$(CONFIG_ALL) += qemu-fsdev-dummy.o
diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
index 6db9fea..33fe822 100644
--- a/fsdev/file-op-9p.h
+++ b/fsdev/file-op-9p.h
@@ -17,6 +17,7 @@
 #include <dirent.h>
 #include <utime.h>
 #include <sys/vfs.h>
+#include "qemu-fsdev-throttle.h"

 #define SM_LOCAL_MODE_BITS    0600
 #define SM_LOCAL_DIR_MODE_BITS    0700
@@ -74,6 +75,7 @@ typedef struct FsDriverEntry {
     char *path;
     int export_flags;
     FileOperations *ops;
+    FsThrottle fst;
 } FsDriverEntry;

 typedef struct FsContext
@@ -83,6 +85,7 @@ typedef struct FsContext
     int export_flags;
     struct xattr_operations **xops;
     struct extended_ops exops;
+    FsThrottle *fst;
     /* fs driver specific data */
     void *private;
 } FsContext;
diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c
index 1dd8c7a..395d497 100644
--- a/fsdev/qemu-fsdev-opts.c
+++ b/fsdev/qemu-fsdev-opts.c
@@ -37,6 +37,82 @@ static QemuOptsList qemu_fsdev_opts = {
         }, {
             .name = "sock_fd",
             .type = QEMU_OPT_NUMBER,
+        }, {
+            .name = "throttling.iops-total",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit total I/O operations per second",
+        },{
+            .name = "throttling.iops-read",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit read operations per second",
+        },{
+            .name = "throttling.iops-write",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit write operations per second",
+        },{
+            .name = "throttling.bps-total",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit total bytes per second",
+        },{
+            .name = "throttling.bps-read",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit read bytes per second",
+        },{
+            .name = "throttling.bps-write",
+            .type = QEMU_OPT_NUMBER,
+            .help = "limit write bytes per second",
+        },{
+            .name = "throttling.iops-total-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations burst",
+        },{
+            .name = "throttling.iops-read-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations read burst",
+        },{
+            .name = "throttling.iops-write-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "I/O operations write burst",
+        },{
+            .name = "throttling.bps-total-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes burst",
+        },{
+            .name = "throttling.bps-read-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes read burst",
+        },{
+            .name = "throttling.bps-write-max",
+            .type = QEMU_OPT_NUMBER,
+            .help = "total bytes write burst",
+        },{
+            .name = "throttling.iops-total-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the iops-total-max burst period, in seconds",
+        },{
+            .name = "throttling.iops-read-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the iops-read-max burst period, in seconds",
+        },{
+            .name = "throttling.iops-write-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the iops-write-max burst period, in seconds",
+        },{
+            .name = "throttling.bps-total-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the bps-total-max burst period, in seconds",
+        },{
+            .name = "throttling.bps-read-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the bps-read-max burst period, in seconds",
+        },{
+            .name = "throttling.bps-write-max-length",
+            .type = QEMU_OPT_NUMBER,
+            .help = "length of the bps-write-max burst period, in seconds",
+        },{
+            .name = "throttling.iops-size",
+            .type = QEMU_OPT_NUMBER,
+            .help = "when limiting by iops max size of an I/O in bytes",
         },

         { /*End of list */ }
diff --git a/fsdev/qemu-fsdev-throttle.c b/fsdev/qemu-fsdev-throttle.c
new file mode 100644
index 0000000..d48d031
--- /dev/null
+++ b/fsdev/qemu-fsdev-throttle.c
@@ -0,0 +1,147 @@
+/*
+ * Fsdev Throttle
+ *
+ * Copyright (C) 2016 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Pradeep Jagadeesh <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.
+ *
+ * See the COPYING file in the top-level directory for details.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "qemu-fsdev-throttle.h"
+
+static bool fsdev_throttle_check_for_wait(FsThrottle *fst, bool is_write)
+{
+   return throttle_schedule_timer(&fst->ts, &fst->tt, is_write);
+}
+
+static void fsdev_throttle_schedule_next_request(FsThrottle *fst, bool 
is_write)
+{
+   if (!qemu_co_queue_empty(&fst->throttled_reqs[is_write])) {
+        if (fsdev_throttle_check_for_wait(fst, is_write)) {
+            return;
+        }
+       qemu_co_queue_next(&fst->throttled_reqs[is_write]);

This calls for a coroutine_fn tag but...

+   }
+}
+

... as Berto already suggested in v6, these functions aren't needed and your
"I just would like to keep these functions" answer isn't convincing enough.
Personally, I'd greatly really prefer the code to be inlined in the callers,
so that we can see the whole throttling/queue logic in one place.

+static void fsdev_throttle_read_timer_cb(void *opaque)
+{
+    FsThrottle *fst = opaque;
+    qemu_co_enter_next(&fst->throttled_reqs[false]);
+}
+
+static void fsdev_throttle_write_timer_cb(void *opaque)
+{
+    FsThrottle *fst = opaque;
+    qemu_co_enter_next(&fst->throttled_reqs[true]);
+}
+
+static void fsdev_parse_io_limit_opts(QemuOpts *opts, FsThrottle *fst)
+{
+    fst->cfg.buckets[THROTTLE_BPS_TOTAL].avg =
+          qemu_opt_get_number(opts, "throttling.bps-total", 0);
+    fst->cfg.buckets[THROTTLE_BPS_READ].avg  =
+          qemu_opt_get_number(opts, "throttling.bps-read", 0);
+    fst->cfg.buckets[THROTTLE_BPS_WRITE].avg =
+          qemu_opt_get_number(opts, "throttling.bps-write", 0);
+    fst->cfg.buckets[THROTTLE_OPS_TOTAL].avg =
+          qemu_opt_get_number(opts, "throttling.iops-total", 0);
+    fst->cfg.buckets[THROTTLE_OPS_READ].avg =
+          qemu_opt_get_number(opts, "throttling.iops-read", 0);
+    fst->cfg.buckets[THROTTLE_OPS_WRITE].avg =
+          qemu_opt_get_number(opts, "throttling.iops-write", 0);
+
+    fst->cfg.buckets[THROTTLE_BPS_TOTAL].max =
+          qemu_opt_get_number(opts, "throttling.bps-total-max", 0);
+    fst->cfg.buckets[THROTTLE_BPS_READ].max  =
+          qemu_opt_get_number(opts, "throttling.bps-read-max", 0);
+    fst->cfg.buckets[THROTTLE_BPS_WRITE].max =
+          qemu_opt_get_number(opts, "throttling.bps-write-max", 0);
+    fst->cfg.buckets[THROTTLE_OPS_TOTAL].max =
+          qemu_opt_get_number(opts, "throttling.iops-total-max", 0);
+    fst->cfg.buckets[THROTTLE_OPS_READ].max =
+          qemu_opt_get_number(opts, "throttling.iops-read-max", 0);
+    fst->cfg.buckets[THROTTLE_OPS_WRITE].max =
+          qemu_opt_get_number(opts, "throttling.iops-write-max", 0);
+
+    fst->cfg.buckets[THROTTLE_BPS_TOTAL].burst_length =
+          qemu_opt_get_number(opts, "throttling.bps-total-max-length", 1);
+    fst->cfg.buckets[THROTTLE_BPS_READ].burst_length  =
+          qemu_opt_get_number(opts, "throttling.bps-read-max-length", 1);
+    fst->cfg.buckets[THROTTLE_BPS_WRITE].burst_length =
+          qemu_opt_get_number(opts, "throttling.bps-write-max-length", 1);
+    fst->cfg.buckets[THROTTLE_OPS_TOTAL].burst_length =
+          qemu_opt_get_number(opts, "throttling.iops-total-max-length", 1);
+    fst->cfg.buckets[THROTTLE_OPS_READ].burst_length =
+          qemu_opt_get_number(opts, "throttling.iops-read-max-length", 1);
+    fst->cfg.buckets[THROTTLE_OPS_WRITE].burst_length =
+          qemu_opt_get_number(opts, "throttling.iops-write-max-length", 1);
+    fst->cfg.op_size =
+          qemu_opt_get_number(opts, "throttling.iops-size", 0);
+}
+
+int fsdev_throttle_configure_iolimits(QemuOpts *opts, FsThrottle *fst)
+{
+    Error *err = NULL;
+
+    /* Parse and set populate the cfg structure */
+    fsdev_parse_io_limit_opts(opts, fst);
+
+    if (!throttle_is_valid(&fst->cfg, &err)) {
+        error_reportf_err(err, "Throttle configuration is not valid: ");
+        return -1;
+    }
+    if (throttle_enabled(&fst->cfg)) {
+        g_assert((fst->aioctx = qemu_get_aio_context()));
+        throttle_init(&fst->ts);
+        throttle_timers_init(&fst->tt,
+                             fst->aioctx,
+                             QEMU_CLOCK_REALTIME,
+                             fsdev_throttle_read_timer_cb,
+                             fsdev_throttle_write_timer_cb,
+                             fst);
+        throttle_config(&fst->ts, &fst->tt, &fst->cfg);
+        qemu_co_queue_init(&fst->throttled_reqs[0]);
+        qemu_co_queue_init(&fst->throttled_reqs[1]);
+   }
+   return 0;
+}
+
+static int get_num_bytes(struct iovec *iov, int iovcnt)
+{
+    int i;
+    unsigned int bytes = 0;
+
+    for (i = 0; i < iovcnt; i++) {
+        bytes += iov[i].iov_len;
+    }
+    return bytes;
+}
+
+void coroutine_fn fsdev_co_throttle_request(FsThrottle *fst, bool is_write,
+                            struct iovec *iov, int iovcnt)
+{
+    if (throttle_enabled(&fst->cfg)) {
+        int bytes = get_num_bytes(iov, iovcnt);
+        bool must_wait = fsdev_throttle_check_for_wait(fst, is_write);
+        if (must_wait || !qemu_co_queue_empty(&fst->throttled_reqs[is_write])) 
{
+            qemu_co_queue_wait(&fst->throttled_reqs[is_write]);
+       }
+       throttle_account(&fst->ts, is_write, bytes);
+
+       fsdev_throttle_schedule_next_request(fst, is_write);
+    }
+}
+
+void fsdev_throttle_cleanup(FsThrottle *fst)
+{
+    throttle_timers_destroy(&fst->tt);
+}
diff --git a/fsdev/qemu-fsdev-throttle.h b/fsdev/qemu-fsdev-throttle.h
new file mode 100644
index 0000000..df4e608
--- /dev/null
+++ b/fsdev/qemu-fsdev-throttle.h
@@ -0,0 +1,37 @@
+/*
+ * Fsdev Throttle
+ *
+ * Copyright (C) 2016 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Pradeep Jagadeesh <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.
+ *
+ * See the COPYING file in the top-level directory for details.
+ *
+ */
+
+#ifndef _FSDEV_THROTTLE_H
+#define _FSDEV_THROTTLE_H
+
+#include "block/aio.h"
+#include "qemu/main-loop.h"
+#include "qemu/coroutine.h"
+#include "qemu/throttle.h"
+
+typedef struct FsThrottle {
+    ThrottleState ts;
+    ThrottleTimers tt;
+    AioContext   *aioctx;
+    ThrottleConfig cfg;
+    CoQueue      throttled_reqs[2];
+} FsThrottle;
+
+int  fsdev_throttle_configure_iolimits(QemuOpts *, FsThrottle *);
+
+void coroutine_fn fsdev_co_throttle_request(FsThrottle *fst, bool is_write,
+                            struct iovec *iov, int iovcnt);
+
+void fsdev_throttle_cleanup(FsThrottle *);
+#endif /* _FSDEV_THROTTLE_H */
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 3f271fc..54459f2 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -436,8 +436,8 @@ static ssize_t local_pwritev(FsContext *ctx, 
V9fsFidOpenState *fs,
                              const struct iovec *iov,
                              int iovcnt, off_t offset)
 {
-    ssize_t ret
-;
+    ssize_t ret;
+

Please push this to a separate patch.

Thanks.

--
Greg

 #ifdef CONFIG_PREADV
     ret = pwritev(fs->fd, iov, iovcnt, offset);
 #else
@@ -1240,6 +1240,11 @@ static int local_parse_opts(QemuOpts *opts, struct 
FsDriverEntry *fse)
         error_report("fsdev: No path specified");
         return -1;
     }
+
+    if (fsdev_throttle_configure_iolimits(opts, &fse->fst) < 0) {
+        return -1;
+    }
+
     fse->path = g_strdup(path);

     return 0;
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index dfe293d..ccf6d0c 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -3490,6 +3490,9 @@ int v9fs_device_realize_common(V9fsState *s, Error **errp)
         error_setg(errp, "share path %s is not a directory", fse->path);
         goto out;
     }
+
+    s->ctx.fst = &fse->fst;
+
     v9fs_path_free(&path);

     rc = 0;
@@ -3504,6 +3507,9 @@ out:

 void v9fs_device_unrealize_common(V9fsState *s, Error **errp)
 {
+    if (throttle_enabled(&s->ctx.fst->cfg)) {
+        fsdev_throttle_cleanup(s->ctx.fst);
+    }
     g_free(s->ctx.fs_root);
     g_free(s->tag);
 }
diff --git a/hw/9pfs/cofile.c b/hw/9pfs/cofile.c
index 10343c0..039031d 100644
--- a/hw/9pfs/cofile.c
+++ b/hw/9pfs/cofile.c
@@ -16,6 +16,7 @@
 #include "qemu/thread.h"
 #include "qemu/coroutine.h"
 #include "coth.h"
+#include "fsdev/qemu-fsdev-throttle.h"

 int v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t st_mode,
                    V9fsStatDotl *v9stat)
@@ -245,6 +246,8 @@ int v9fs_co_pwritev(V9fsPDU *pdu, V9fsFidState *fidp,
     if (v9fs_request_cancelled(pdu)) {
         return -EINTR;
     }
+
+    fsdev_co_throttle_request(s->ctx.fst, true, iov, iovcnt);
     v9fs_co_run_in_worker(
         {
             err = s->ops->pwritev(&s->ctx, &fidp->fs, iov, iovcnt, offset);
@@ -264,6 +267,8 @@ int v9fs_co_preadv(V9fsPDU *pdu, V9fsFidState *fidp,
     if (v9fs_request_cancelled(pdu)) {
         return -EINTR;
     }
+
+    fsdev_co_throttle_request(s->ctx.fst, false, iov, iovcnt);
     v9fs_co_run_in_worker(
         {
             err = s->ops->preadv(&s->ctx, &fidp->fs, iov, iovcnt, offset);





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