Messages in this thread | | | Date | Tue, 5 Jul 2022 12:01:58 +0300 | Subject | Re: [PATCH v4 1/1] Create debugfs file with virtio balloon usage information | From | Alexander Atanasov <> |
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Hello,
On 05/07/2022 11:59, Michael S. Tsirkin wrote: > On Tue, Jul 05, 2022 at 08:36:37AM +0000, Alexander Atanasov wrote: >> 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 <alexander.atanasov@virtuozzo.com> >> --- >> drivers/virtio/virtio_balloon.c | 77 +++++++++++++++++++++++++++++ >> include/uapi/linux/virtio_balloon.h | 1 + >> 2 files changed, 78 insertions(+) >> >> V2: >> - fixed coding style >> - removed pretty print >> V3: >> - removed dublicate of features >> - comment about balooned_pages more clear >> - convert host pages to balloon pages >> V4: >> - added a define for BALLOON_PAGE_SIZE to make things clear >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index b9737da6c4dd..dc4ad584b947 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -10,6 +10,7 @@ >> #include <linux/virtio_balloon.h> >> #include <linux/swap.h> >> #include <linux/workqueue.h> >> +#include <linux/debugfs.h> >> #include <linux/delay.h> >> #include <linux/slab.h> >> #include <linux/module.h> >> @@ -731,6 +732,77 @@ static void report_free_page_func(struct work_struct *work) >> } >> } >> >> +/* >> + * DEBUGFS Interface >> + */ >> +#ifdef CONFIG_DEBUG_FS >> + >> +#define guest_to_balloon_pages(i) ((i)*VIRTIO_BALLOON_PAGES_PER_PAGE) >> +/** >> + * 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: %d\n", "page_size", VIRTIO_BALLOON_PAGE_SIZE); >> + >> + virtio_cread_le(b->vdev, struct virtio_balloon_config, actual, >> + &num_pages); >> + /* >> + * Pages allocated by host from the guest memory. >> + * Host inflates the balloon to get more memory. >> + * Guest needs to deflate the balloon to get more memory. >> + */ >> + 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", >> + guest_to_balloon_pages(i.totalram)); >> + >> + /* Current memory for the guest */ >> + seq_printf(f, "%-22s: %lu\n", "current_pages", >> + guest_to_balloon_pages(i.totalram) - num_pages); >> + >> + 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 +1091,9 @@ 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 +1140,8 @@ 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)) >> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h >> index ddaa45e723c4..f3ff7c4e5884 100644 >> --- a/include/uapi/linux/virtio_balloon.h >> +++ b/include/uapi/linux/virtio_balloon.h >> @@ -40,6 +40,7 @@ >> >> /* Size of a PFN in the balloon interface. */ >> #define VIRTIO_BALLOON_PFN_SHIFT 12 >> +#define VIRTIO_BALLOON_PAGE_SIZE (1<<VIRTIO_BALLOON_PFN_SHIFT) >> #define VIRTIO_BALLOON_CMD_ID_STOP 0 >> #define VIRTIO_BALLOON_CMD_ID_DONE 1 > Did you run checkpatch on this?
Sure, i did:
scripts/checkpatch.pl ../outgoing/v4-0001-Create-debugfs-file-with-virtio-balloon-usage-inf.patch total: 0 errors, 0 warnings, 108 lines checked
../outgoing/v4-0001-Create-debugfs-file-with-virtio-balloon-usage-inf.patch has no obvious style problems and is ready for submission.
-- Regards, Alexander Atanasov
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