What is an alternative for zcache?
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I want to use a high-speed swap device or zram as "page cache", so that page data can be dropped automatically when the system is out of memory.
Apparently, zcache has been discontinued. Is there an available alternative? If yes, which one?
bcache doesn't seem to drop data when there's no memory available.
linux-kernel swap cache zram
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
add a comment |
I want to use a high-speed swap device or zram as "page cache", so that page data can be dropped automatically when the system is out of memory.
Apparently, zcache has been discontinued. Is there an available alternative? If yes, which one?
bcache doesn't seem to drop data when there's no memory available.
linux-kernel swap cache zram
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,bcachehas nothing to do with it.
– Adam Ryczkowski
Jun 27 '17 at 14:23
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) withswaponandswapoffcommands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.
– Adam Ryczkowski
Jun 30 '17 at 16:59
I'm sorry for my express way,in fact I trying find a alternative forzcache@AdamRyczkowski thank you.
– illiterate
Jul 1 '17 at 4:49
add a comment |
I want to use a high-speed swap device or zram as "page cache", so that page data can be dropped automatically when the system is out of memory.
Apparently, zcache has been discontinued. Is there an available alternative? If yes, which one?
bcache doesn't seem to drop data when there's no memory available.
linux-kernel swap cache zram
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
I want to use a high-speed swap device or zram as "page cache", so that page data can be dropped automatically when the system is out of memory.
Apparently, zcache has been discontinued. Is there an available alternative? If yes, which one?
bcache doesn't seem to drop data when there's no memory available.
linux-kernel swap cache zram
linux-kernel swap cache zram
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
edited Jul 23 '17 at 13:19
illiterate
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
asked Jun 27 '17 at 8:34
illiterateilliterate
8211
8211
How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,bcachehas nothing to do with it.
– Adam Ryczkowski
Jun 27 '17 at 14:23
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) withswaponandswapoffcommands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.
– Adam Ryczkowski
Jun 30 '17 at 16:59
I'm sorry for my express way,in fact I trying find a alternative forzcache@AdamRyczkowski thank you.
– illiterate
Jul 1 '17 at 4:49
add a comment |
How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,bcachehas nothing to do with it.
– Adam Ryczkowski
Jun 27 '17 at 14:23
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) withswaponandswapoffcommands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.
– Adam Ryczkowski
Jun 30 '17 at 16:59
I'm sorry for my express way,in fact I trying find a alternative forzcache@AdamRyczkowski thank you.
– illiterate
Jul 1 '17 at 4:49
How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,
bcache has nothing to do with it.– Adam Ryczkowski
Jun 27 '17 at 14:23
How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,
bcache has nothing to do with it.– Adam Ryczkowski
Jun 27 '17 at 14:23
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) with
swapon and swapoff commands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.– Adam Ryczkowski
Jun 30 '17 at 16:59
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) with
swapon and swapoff commands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.– Adam Ryczkowski
Jun 30 '17 at 16:59
I'm sorry for my express way,in fact I trying find a alternative for
zcache @AdamRyczkowski thank you.– illiterate
Jul 1 '17 at 4:49
I'm sorry for my express way,in fact I trying find a alternative for
zcache @AdamRyczkowski thank you.– illiterate
Jul 1 '17 at 4:49
add a comment |
1 Answer
1
active
oldest
votes
Indeed zcache appears to have been discontinued, as it was removed from kernel 3.11 for being effectively obsolete. The commit message of zcache removal reads
staging: zcache: delete it
zcache is obsolete and not used anymore, Bob Liu has rewritten it and
is submitting it for inclusion through the main -mm tree, as it should
have been done in the first place...
It appears that Bob Liu's submission never got into mainline.
Now, the way I understand it, the page cache is automatically "dropped" (cleared) in an out-of-memory scenario. zcache actually implemented compression so it could maintain more filesystem pages (also known as "vfs cache" or "inode/dentry cache") before being dropped.
The Linux kernel has zswap today that implements compressed disk-based swapping, but doesn't compress filesystem pages.
I am not aware of a current day alternative for zcache.
Perhaps as a workaround, if you are concerned with performance degradation due to filesystem pages being freed, consider tuning vm.vfs_cache_pressure as instructed here.
For normal workloads it's safe to just settle with zswap.
Additional reading:
- zram vs zswap vs zcache Ultimate guide: when to use which one
- Zswap, Zram, Zcache desktop usage scenarios
- zswap (Arch Linux Wiki)
- Cleancache and Frontswap (LWN)
- The Case for Compressed Caching in Virtual Memory Systems
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
add a comment |
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1 Answer
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1 Answer
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Indeed zcache appears to have been discontinued, as it was removed from kernel 3.11 for being effectively obsolete. The commit message of zcache removal reads
staging: zcache: delete it
zcache is obsolete and not used anymore, Bob Liu has rewritten it and
is submitting it for inclusion through the main -mm tree, as it should
have been done in the first place...
It appears that Bob Liu's submission never got into mainline.
Now, the way I understand it, the page cache is automatically "dropped" (cleared) in an out-of-memory scenario. zcache actually implemented compression so it could maintain more filesystem pages (also known as "vfs cache" or "inode/dentry cache") before being dropped.
The Linux kernel has zswap today that implements compressed disk-based swapping, but doesn't compress filesystem pages.
I am not aware of a current day alternative for zcache.
Perhaps as a workaround, if you are concerned with performance degradation due to filesystem pages being freed, consider tuning vm.vfs_cache_pressure as instructed here.
For normal workloads it's safe to just settle with zswap.
Additional reading:
- zram vs zswap vs zcache Ultimate guide: when to use which one
- Zswap, Zram, Zcache desktop usage scenarios
- zswap (Arch Linux Wiki)
- Cleancache and Frontswap (LWN)
- The Case for Compressed Caching in Virtual Memory Systems
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
add a comment |
Indeed zcache appears to have been discontinued, as it was removed from kernel 3.11 for being effectively obsolete. The commit message of zcache removal reads
staging: zcache: delete it
zcache is obsolete and not used anymore, Bob Liu has rewritten it and
is submitting it for inclusion through the main -mm tree, as it should
have been done in the first place...
It appears that Bob Liu's submission never got into mainline.
Now, the way I understand it, the page cache is automatically "dropped" (cleared) in an out-of-memory scenario. zcache actually implemented compression so it could maintain more filesystem pages (also known as "vfs cache" or "inode/dentry cache") before being dropped.
The Linux kernel has zswap today that implements compressed disk-based swapping, but doesn't compress filesystem pages.
I am not aware of a current day alternative for zcache.
Perhaps as a workaround, if you are concerned with performance degradation due to filesystem pages being freed, consider tuning vm.vfs_cache_pressure as instructed here.
For normal workloads it's safe to just settle with zswap.
Additional reading:
- zram vs zswap vs zcache Ultimate guide: when to use which one
- Zswap, Zram, Zcache desktop usage scenarios
- zswap (Arch Linux Wiki)
- Cleancache and Frontswap (LWN)
- The Case for Compressed Caching in Virtual Memory Systems
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
add a comment |
Indeed zcache appears to have been discontinued, as it was removed from kernel 3.11 for being effectively obsolete. The commit message of zcache removal reads
staging: zcache: delete it
zcache is obsolete and not used anymore, Bob Liu has rewritten it and
is submitting it for inclusion through the main -mm tree, as it should
have been done in the first place...
It appears that Bob Liu's submission never got into mainline.
Now, the way I understand it, the page cache is automatically "dropped" (cleared) in an out-of-memory scenario. zcache actually implemented compression so it could maintain more filesystem pages (also known as "vfs cache" or "inode/dentry cache") before being dropped.
The Linux kernel has zswap today that implements compressed disk-based swapping, but doesn't compress filesystem pages.
I am not aware of a current day alternative for zcache.
Perhaps as a workaround, if you are concerned with performance degradation due to filesystem pages being freed, consider tuning vm.vfs_cache_pressure as instructed here.
For normal workloads it's safe to just settle with zswap.
Additional reading:
- zram vs zswap vs zcache Ultimate guide: when to use which one
- Zswap, Zram, Zcache desktop usage scenarios
- zswap (Arch Linux Wiki)
- Cleancache and Frontswap (LWN)
- The Case for Compressed Caching in Virtual Memory Systems
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
Indeed zcache appears to have been discontinued, as it was removed from kernel 3.11 for being effectively obsolete. The commit message of zcache removal reads
staging: zcache: delete it
zcache is obsolete and not used anymore, Bob Liu has rewritten it and
is submitting it for inclusion through the main -mm tree, as it should
have been done in the first place...
It appears that Bob Liu's submission never got into mainline.
Now, the way I understand it, the page cache is automatically "dropped" (cleared) in an out-of-memory scenario. zcache actually implemented compression so it could maintain more filesystem pages (also known as "vfs cache" or "inode/dentry cache") before being dropped.
The Linux kernel has zswap today that implements compressed disk-based swapping, but doesn't compress filesystem pages.
I am not aware of a current day alternative for zcache.
Perhaps as a workaround, if you are concerned with performance degradation due to filesystem pages being freed, consider tuning vm.vfs_cache_pressure as instructed here.
For normal workloads it's safe to just settle with zswap.
Additional reading:
- zram vs zswap vs zcache Ultimate guide: when to use which one
- Zswap, Zram, Zcache desktop usage scenarios
- zswap (Arch Linux Wiki)
- Cleancache and Frontswap (LWN)
- The Case for Compressed Caching in Virtual Memory Systems
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
edited Jan 26 at 19:58
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
answered Jul 1 '17 at 5:58
Marc.2377Marc.2377
285224
285224
add a comment |
add a comment |
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How do you define "page cache"? Do you mean memory management scheme, a.k.a. swap? If so,
bcachehas nothing to do with it.– Adam Ryczkowski
Jun 27 '17 at 14:23
@AdamRyczkowski In computing, a page cache, sometimes also called disk cache
– illiterate
Jun 28 '17 at 7:47
You English is difficult to understand, and you seem to mix unrelated concepts, so the noise level in your question is rather high. That's why I asked for clarification.
– Adam Ryczkowski
Jun 30 '17 at 16:57
You ask about how to use swap device as "page cache". You control which swap devices the kernel should use (and their priorities) with
swaponandswapoffcommands. It doesn't matter what is the actual storage for the device, whether it is a zram, disk partition, or bcache.– Adam Ryczkowski
Jun 30 '17 at 16:59
I'm sorry for my express way,in fact I trying find a alternative for
zcache@AdamRyczkowski thank you.– illiterate
Jul 1 '17 at 4:49