* Re: [pbs-devel] [PATCH proxmox-backup-qemu 8/9] add shared_cache module
@ 2021-06-07 8:07 Wolfgang Bumiller
0 siblings, 0 replies; 4+ messages in thread
From: Wolfgang Bumiller @ 2021-06-07 8:07 UTC (permalink / raw)
To: Stefan Reiter; +Cc: pve-devel, pbs-devel
> On 06/07/2021 10:03 AM Stefan Reiter <s.reiter@proxmox.com> wrote:
>
>
> On 6/4/21 2:16 PM, Wolfgang Bumiller wrote:
> > On Wed, Jun 02, 2021 at 04:38:32PM +0200, Stefan Reiter wrote:
> >> Provides a shared AsyncLruCache of 256MB (w/ 4MB chunks) that can be
> >> used by multiple readers at the same time. It is dropped once no more
> >> readers exist, so the memory gets freed if all QEMU block/pbs instances
> >> disappear.
> >>
> >> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> >> ---
> >> src/lib.rs | 7 ++++++-
> >> src/shared_cache.rs | 36 ++++++++++++++++++++++++++++++++++++
> >> 2 files changed, 42 insertions(+), 1 deletion(-)
> >> create mode 100644 src/shared_cache.rs
> >>
> >> diff --git a/src/lib.rs b/src/lib.rs
> >> index 05d7b58..aa167f7 100644
> >> --- a/src/lib.rs
> >> +++ b/src/lib.rs
> >> @@ -25,6 +25,7 @@ mod restore;
> >> use restore::*;
> >>
> >> mod tools;
> >> +mod shared_cache;
> >>
> >> pub const PROXMOX_BACKUP_DEFAULT_CHUNK_SIZE: u64 = 1024*1024*4;
> >>
> >> @@ -804,7 +805,11 @@ pub extern "C" fn proxmox_restore_connect_async(
> >> pub extern "C" fn proxmox_restore_disconnect(handle: *mut ProxmoxRestoreHandle) {
> >>
> >> let restore_task = handle as * mut Arc<RestoreTask>;
> >> - unsafe { Box::from_raw(restore_task) }; //drop(restore_task)
> >> + let restore_task = unsafe { Box::from_raw(restore_task) };
> >> + drop(restore_task);
> >> +
> >> + // after dropping, cache may be unused (if no other handles open)
> >> + shared_cache::shared_chunk_cache_cleanup();
> >> }
> >>
> >> /// Restore an image (sync)
> >> diff --git a/src/shared_cache.rs b/src/shared_cache.rs
> >> new file mode 100644
> >> index 0000000..bebae5b
> >> --- /dev/null
> >> +++ b/src/shared_cache.rs
> >> @@ -0,0 +1,36 @@
> >> +use once_cell::sync::OnceCell;
> >> +use proxmox_backup::backup::ChunkCache;
> >> +use proxmox_backup::tools::async_lru_cache::AsyncLruCache;
> >> +use std::sync::{Arc, Mutex};
> >> +
> >> +const SHARED_CACHE_CAPACITY: usize = 64; // 256 MB
> >> +static SHARED_CACHE: OnceCell<Mutex<Option<ChunkCache>>> = OnceCell::new();
> >
> > OnceCell *and* Option is a bit too much, `get_shared_chunk_chache()` can
> > just initialize it in `get_or_init()` directly.
> >
>
> Then how do we drop the ChunkCache? I used OnceCell since
> std::sync::Mutex doesn't seem to have a 'const new', not because of
> 'Option' semantics.
Right. I forgot about the cleanup.
As for the const Mutex::new... don't we have parking lot in our dependency tree already? ;-)
But yeah, I guess it's fine.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [pbs-devel] [PATCH proxmox-backup-qemu 8/9] add shared_cache module
2021-06-04 12:16 ` Wolfgang Bumiller
@ 2021-06-07 8:03 ` Stefan Reiter
0 siblings, 0 replies; 4+ messages in thread
From: Stefan Reiter @ 2021-06-07 8:03 UTC (permalink / raw)
To: Wolfgang Bumiller; +Cc: pve-devel, pbs-devel
On 6/4/21 2:16 PM, Wolfgang Bumiller wrote:
> On Wed, Jun 02, 2021 at 04:38:32PM +0200, Stefan Reiter wrote:
>> Provides a shared AsyncLruCache of 256MB (w/ 4MB chunks) that can be
>> used by multiple readers at the same time. It is dropped once no more
>> readers exist, so the memory gets freed if all QEMU block/pbs instances
>> disappear.
>>
>> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
>> ---
>> src/lib.rs | 7 ++++++-
>> src/shared_cache.rs | 36 ++++++++++++++++++++++++++++++++++++
>> 2 files changed, 42 insertions(+), 1 deletion(-)
>> create mode 100644 src/shared_cache.rs
>>
>> diff --git a/src/lib.rs b/src/lib.rs
>> index 05d7b58..aa167f7 100644
>> --- a/src/lib.rs
>> +++ b/src/lib.rs
>> @@ -25,6 +25,7 @@ mod restore;
>> use restore::*;
>>
>> mod tools;
>> +mod shared_cache;
>>
>> pub const PROXMOX_BACKUP_DEFAULT_CHUNK_SIZE: u64 = 1024*1024*4;
>>
>> @@ -804,7 +805,11 @@ pub extern "C" fn proxmox_restore_connect_async(
>> pub extern "C" fn proxmox_restore_disconnect(handle: *mut ProxmoxRestoreHandle) {
>>
>> let restore_task = handle as * mut Arc<RestoreTask>;
>> - unsafe { Box::from_raw(restore_task) }; //drop(restore_task)
>> + let restore_task = unsafe { Box::from_raw(restore_task) };
>> + drop(restore_task);
>> +
>> + // after dropping, cache may be unused (if no other handles open)
>> + shared_cache::shared_chunk_cache_cleanup();
>> }
>>
>> /// Restore an image (sync)
>> diff --git a/src/shared_cache.rs b/src/shared_cache.rs
>> new file mode 100644
>> index 0000000..bebae5b
>> --- /dev/null
>> +++ b/src/shared_cache.rs
>> @@ -0,0 +1,36 @@
>> +use once_cell::sync::OnceCell;
>> +use proxmox_backup::backup::ChunkCache;
>> +use proxmox_backup::tools::async_lru_cache::AsyncLruCache;
>> +use std::sync::{Arc, Mutex};
>> +
>> +const SHARED_CACHE_CAPACITY: usize = 64; // 256 MB
>> +static SHARED_CACHE: OnceCell<Mutex<Option<ChunkCache>>> = OnceCell::new();
>
> OnceCell *and* Option is a bit too much, `get_shared_chunk_chache()` can
> just initialize it in `get_or_init()` directly.
>
Then how do we drop the ChunkCache? I used OnceCell since
std::sync::Mutex doesn't seem to have a 'const new', not because of
'Option' semantics.
>> +
>> +pub fn get_shared_chunk_cache() -> ChunkCache {
>> + let mut guard = SHARED_CACHE
>> + .get_or_init(|| Mutex::new(None))
>> + .lock()
>> + .unwrap();
>> + match &*guard {
>> + Some(cache) => Arc::clone(cache),
>> + None => {
>> + let cache = Arc::new(AsyncLruCache::new(SHARED_CACHE_CAPACITY));
>> + *guard = Some(Arc::clone(&cache));
>> + cache
>> + }
>> + }
>> +}
>> +
>> +pub fn shared_chunk_cache_cleanup() {
>> + let mut guard = SHARED_CACHE
>> + .get_or_init(|| Mutex::new(None))
>> + .lock()
>> + .unwrap();
>> + if let Some(arc) = guard.as_ref() {
>> + let refcount = Arc::strong_count(arc);
>> + if refcount == 1 {
>> + // no one else is using the cache anymore, drop it
>> + let _drop = guard.take();
>> + }
>> + }
>> +}
>> --
>> 2.30.2
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [pbs-devel] [PATCH proxmox-backup-qemu 8/9] add shared_cache module
2021-06-02 14:38 ` [pbs-devel] [PATCH proxmox-backup-qemu 8/9] add shared_cache module Stefan Reiter
@ 2021-06-04 12:16 ` Wolfgang Bumiller
2021-06-07 8:03 ` Stefan Reiter
0 siblings, 1 reply; 4+ messages in thread
From: Wolfgang Bumiller @ 2021-06-04 12:16 UTC (permalink / raw)
To: Stefan Reiter; +Cc: pve-devel, pbs-devel
On Wed, Jun 02, 2021 at 04:38:32PM +0200, Stefan Reiter wrote:
> Provides a shared AsyncLruCache of 256MB (w/ 4MB chunks) that can be
> used by multiple readers at the same time. It is dropped once no more
> readers exist, so the memory gets freed if all QEMU block/pbs instances
> disappear.
>
> Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
> ---
> src/lib.rs | 7 ++++++-
> src/shared_cache.rs | 36 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 42 insertions(+), 1 deletion(-)
> create mode 100644 src/shared_cache.rs
>
> diff --git a/src/lib.rs b/src/lib.rs
> index 05d7b58..aa167f7 100644
> --- a/src/lib.rs
> +++ b/src/lib.rs
> @@ -25,6 +25,7 @@ mod restore;
> use restore::*;
>
> mod tools;
> +mod shared_cache;
>
> pub const PROXMOX_BACKUP_DEFAULT_CHUNK_SIZE: u64 = 1024*1024*4;
>
> @@ -804,7 +805,11 @@ pub extern "C" fn proxmox_restore_connect_async(
> pub extern "C" fn proxmox_restore_disconnect(handle: *mut ProxmoxRestoreHandle) {
>
> let restore_task = handle as * mut Arc<RestoreTask>;
> - unsafe { Box::from_raw(restore_task) }; //drop(restore_task)
> + let restore_task = unsafe { Box::from_raw(restore_task) };
> + drop(restore_task);
> +
> + // after dropping, cache may be unused (if no other handles open)
> + shared_cache::shared_chunk_cache_cleanup();
> }
>
> /// Restore an image (sync)
> diff --git a/src/shared_cache.rs b/src/shared_cache.rs
> new file mode 100644
> index 0000000..bebae5b
> --- /dev/null
> +++ b/src/shared_cache.rs
> @@ -0,0 +1,36 @@
> +use once_cell::sync::OnceCell;
> +use proxmox_backup::backup::ChunkCache;
> +use proxmox_backup::tools::async_lru_cache::AsyncLruCache;
> +use std::sync::{Arc, Mutex};
> +
> +const SHARED_CACHE_CAPACITY: usize = 64; // 256 MB
> +static SHARED_CACHE: OnceCell<Mutex<Option<ChunkCache>>> = OnceCell::new();
OnceCell *and* Option is a bit too much, `get_shared_chunk_chache()` can
just initialize it in `get_or_init()` directly.
> +
> +pub fn get_shared_chunk_cache() -> ChunkCache {
> + let mut guard = SHARED_CACHE
> + .get_or_init(|| Mutex::new(None))
> + .lock()
> + .unwrap();
> + match &*guard {
> + Some(cache) => Arc::clone(cache),
> + None => {
> + let cache = Arc::new(AsyncLruCache::new(SHARED_CACHE_CAPACITY));
> + *guard = Some(Arc::clone(&cache));
> + cache
> + }
> + }
> +}
> +
> +pub fn shared_chunk_cache_cleanup() {
> + let mut guard = SHARED_CACHE
> + .get_or_init(|| Mutex::new(None))
> + .lock()
> + .unwrap();
> + if let Some(arc) = guard.as_ref() {
> + let refcount = Arc::strong_count(arc);
> + if refcount == 1 {
> + // no one else is using the cache anymore, drop it
> + let _drop = guard.take();
> + }
> + }
> +}
> --
> 2.30.2
^ permalink raw reply [flat|nested] 4+ messages in thread
* [pbs-devel] [PATCH proxmox-backup-qemu 8/9] add shared_cache module
2021-06-02 14:38 [pbs-devel] [PATCH 0/9] Improve live-restore speed and replace AsyncIndexReader Stefan Reiter
@ 2021-06-02 14:38 ` Stefan Reiter
2021-06-04 12:16 ` Wolfgang Bumiller
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Reiter @ 2021-06-02 14:38 UTC (permalink / raw)
To: pve-devel, pbs-devel
Provides a shared AsyncLruCache of 256MB (w/ 4MB chunks) that can be
used by multiple readers at the same time. It is dropped once no more
readers exist, so the memory gets freed if all QEMU block/pbs instances
disappear.
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---
src/lib.rs | 7 ++++++-
src/shared_cache.rs | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)
create mode 100644 src/shared_cache.rs
diff --git a/src/lib.rs b/src/lib.rs
index 05d7b58..aa167f7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -25,6 +25,7 @@ mod restore;
use restore::*;
mod tools;
+mod shared_cache;
pub const PROXMOX_BACKUP_DEFAULT_CHUNK_SIZE: u64 = 1024*1024*4;
@@ -804,7 +805,11 @@ pub extern "C" fn proxmox_restore_connect_async(
pub extern "C" fn proxmox_restore_disconnect(handle: *mut ProxmoxRestoreHandle) {
let restore_task = handle as * mut Arc<RestoreTask>;
- unsafe { Box::from_raw(restore_task) }; //drop(restore_task)
+ let restore_task = unsafe { Box::from_raw(restore_task) };
+ drop(restore_task);
+
+ // after dropping, cache may be unused (if no other handles open)
+ shared_cache::shared_chunk_cache_cleanup();
}
/// Restore an image (sync)
diff --git a/src/shared_cache.rs b/src/shared_cache.rs
new file mode 100644
index 0000000..bebae5b
--- /dev/null
+++ b/src/shared_cache.rs
@@ -0,0 +1,36 @@
+use once_cell::sync::OnceCell;
+use proxmox_backup::backup::ChunkCache;
+use proxmox_backup::tools::async_lru_cache::AsyncLruCache;
+use std::sync::{Arc, Mutex};
+
+const SHARED_CACHE_CAPACITY: usize = 64; // 256 MB
+static SHARED_CACHE: OnceCell<Mutex<Option<ChunkCache>>> = OnceCell::new();
+
+pub fn get_shared_chunk_cache() -> ChunkCache {
+ let mut guard = SHARED_CACHE
+ .get_or_init(|| Mutex::new(None))
+ .lock()
+ .unwrap();
+ match &*guard {
+ Some(cache) => Arc::clone(cache),
+ None => {
+ let cache = Arc::new(AsyncLruCache::new(SHARED_CACHE_CAPACITY));
+ *guard = Some(Arc::clone(&cache));
+ cache
+ }
+ }
+}
+
+pub fn shared_chunk_cache_cleanup() {
+ let mut guard = SHARED_CACHE
+ .get_or_init(|| Mutex::new(None))
+ .lock()
+ .unwrap();
+ if let Some(arc) = guard.as_ref() {
+ let refcount = Arc::strong_count(arc);
+ if refcount == 1 {
+ // no one else is using the cache anymore, drop it
+ let _drop = guard.take();
+ }
+ }
+}
--
2.30.2
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