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Tsirkin" To: alexander.atanasov@virtuozzo.com Subject: Re: [PATCH 1/1] Create debugfs file with virtio balloon usage information Message-ID: <20220627085838-mutt-send-email-mst@kernel.org> References: <20220627122038.1921522-1-alexander.atanasov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20220627122038.1921522-1-alexander.atanasov@virtuozzo.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: virtualization@lists.linux-foundation.org, kernel@openvz.org, linux-kernel@vger.kernel.org X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Mon, Jun 27, 2022 at 12:20:38PM +0000, alexander.atanasov@virtuozzo.com wrote: > From: Alexander Atanasov > > Allow the guest to know how much it is ballooned by the host. > It is useful when debugging out of memory conditions. > > When host gets back memory from the guest it is accounted > as used memory in the guest but the guest have no way to know > how much it is actually ballooned. > > Signed-off-by: Alexander Atanasov > --- > drivers/virtio/virtio_balloon.c | 91 +++++++++++++++++++++++++++++++++ > 1 file changed, 91 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index b9737da6c4dd..a32a52c28a1f 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -10,6 +10,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -731,6 +732,91 @@ static void report_free_page_func(struct work_struct *work) > } > } > > +/* > + * DEBUGFS Interface > + */ > +#ifdef CONFIG_DEBUG_FS > + > +/** > + * virtio_balloon_debug_show - shows statistics of balloon operations. > + * @f: pointer to the &struct seq_file. > + * @offset: ignored. > + * > + * Provides the statistics that can be accessed in virtio-balloon in the debugfs. > + * > + * Return: zero on success or an error code. > + */ > +static int virtio_balloon_debug_show(struct seq_file *f, void *offset) > +{ > + struct virtio_balloon *b = f->private; > + u32 num_pages; > + struct sysinfo i; > + > + si_meminfo(&i); > + > + seq_printf(f, "%-22s:", "capabilities"); why aren't features in sysfs sufficient for this? pretty printing can be done in userspace ... > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST)) > + seq_puts(f, " tell_host"); > + > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_STATS_VQ)) > + seq_puts(f, " stats"); > + > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) > + seq_puts(f, " deflate_on_oom"); > + > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) > + seq_puts(f, " free_page_hint"); > + > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_PAGE_POISON)) > + seq_puts(f, " page_poison"); > + > + if (virtio_has_feature(b->vdev, VIRTIO_BALLOON_F_REPORTING)) > + seq_puts(f, " reporting"); > + > + seq_puts(f, "\n"); > + > + seq_printf(f, "%-22s: %d\n", "page_size", 4096); > + > + virtio_cread_le(b->vdev, struct virtio_balloon_config, actual, > + &num_pages); > + /* Memory returned to host or amount we can inflate if possible */ > + seq_printf(f, "%-22s: %u\n", "ballooned_pages", num_pages); > + > + /* Total Memory for the guest from host */ > + seq_printf(f, "%-22s: %lu\n", "total_pages", i.totalram); > + > + /* Current memory for the guest */ > + seq_printf(f, "%-22s: %lu\n", "current_pages", i.totalram-num_pages); spaces around - > + > + return 0; > +} > + > +DEFINE_SHOW_ATTRIBUTE(virtio_balloon_debug); > + > +static void virtio_balloon_debugfs_init(struct virtio_balloon *b) > +{ > + debugfs_create_file("virtio-balloon", 0444, NULL, b, > + &virtio_balloon_debug_fops); > +} > + > +static void virtio_balloon_debugfs_exit(struct virtio_balloon *b) > +{ > + debugfs_remove(debugfs_lookup("virtio-balloon", NULL)); > +} > + > +#else > + > +static inline void virtio_balloon_debugfs_init(struct virtio_balloon *b) > +{ > +} > + > +static inline void virtio_balloon_debugfs_exit(struct virtio_balloon *b) > +{ > +} > + > +#endif /* CONFIG_DEBUG_FS */ > + > #ifdef CONFIG_BALLOON_COMPACTION > /* > * virtballoon_migratepage - perform the balloon page migration on behalf of > @@ -1019,6 +1105,9 @@ static int virtballoon_probe(struct virtio_device *vdev) > > if (towards_target(vb)) > virtballoon_changed(vdev); > + > + virtio_balloon_debugfs_init(vb); > + > return 0; > > out_unregister_oom: > @@ -1065,6 +1154,8 @@ static void virtballoon_remove(struct virtio_device *vdev) > { > struct virtio_balloon *vb = vdev->priv; > > + virtio_balloon_debugfs_exit(vb); > + > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) > page_reporting_unregister(&vb->pr_dev_info); > if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) > -- > 2.25.1 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization