| Message ID | 20180530132137.9530-1-monkeh@monkeh.net |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [OpenWrt-Devel] config: extend small_flash feature | expand |
On Wed, May 30, 2018 at 3:21 PM, Alex Maclean <monkeh@monkeh.net> wrote:
> change the squashfs block size to 1024KiB.
This might cause a problem with memory. You might also want to change
CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE from 3 to 1
in the kernel config.
https://cateee.net/lkddb/web-lkddb/SQUASHFS_FRAGMENT_CACHE_SIZE.html
This defines the blocks that are stored decompressed in memory, as far
as I know this memory is not easily reclaimable and you might run into
issues with a cache size of 3 and 1024kb blocks.
If someone might want to some tests on ar71xx - cat /proc/meminfo -
MemAvailable should be higher after doing something like find /usr |
xargs md5sum
Maybe I'll find the time to do some tests, but this has quite an
impact on free memory for 32mb devices.
regards
Martin
On 30.05.2018 20:22, Martin Tippmann wrote: > find /usr | > xargs md5sum I made the test on tl-wr841n-v9 with luci selected these are the changes to squashfs --- a/config/Config-images.in +++ b/config/Config-images.in @@ -149,8 +149,15 @@ menu "Target Images" int "Block size (in KiB)" depends on TARGET_ROOTFS_SQUASHFS default 64 if LOW_MEMORY_FOOTPRINT + default 1024 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT) default 256 + config SQUASHFS_FRAGMENT_CACHE_SIZE + int "Number of fragments cached" + depends on TARGET_ROOTFS_SQUASHFS + default 1 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT) + default 3 + menuconfig TARGET_ROOTFS_UBIFS bool "ubifs" default y if USES_UBIFS the results: after boot root@OpenWrt:/# df -h Filesystem Size Used Available Use% Mounted on /dev/root 3.0M 3.0M 0 100% /rom tmpfs 13.4M 76.0K 13.4M 1% /tmp tmpfs 13.4M 48.0K 13.4M 0% /tmp/root tmpfs 512.0K 0 512.0K 0% /dev /dev/mtdblock4 320.0K 220.0K 100.0K 69% /overlay overlayfs:/overlay 320.0K 220.0K 100.0K 69% / root@OpenWrt:/# free total used free shared buffers cached Mem: 27520 23920 3600 124 2112 5748 -/+ buffers/cache: 16060 11460 Swap: 0 0 0 root@OpenWrt:/# cat /proc/meminfo MemTotal: 27520 kB MemFree: 3536 kB MemAvailable: 9064 kB Buffers: 2112 kB Cached: 5748 kB SwapCached: 0 kB Active: 5892 kB Inactive: 3120 kB Active(anon): 1252 kB Inactive(anon): 24 kB Active(file): 4640 kB Inactive(file): 3096 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 1160 kB Mapped: 1784 kB Shmem: 124 kB Slab: 8876 kB SReclaimable: 1216 kB SUnreclaim: 7660 kB KernelStack: 304 kB PageTables: 208 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 13760 kB Committed_AS: 3916 kB VmallocTotal: 1048372 kB VmallocUsed: 0 kB VmallocChunk: 0 kB after, ran 3 times MemTotal: 27520 kB MemFree: 1548 kB MemAvailable: 8880 kB Buffers: 2112 kB Cached: 7268 kB SwapCached: 0 kB Active: 9612 kB Inactive: 832 kB Active(anon): 1164 kB Inactive(anon): 24 kB Active(file): 8448 kB Inactive(file): 808 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 1072 kB Mapped: 1688 kB Shmem: 124 kB Slab: 9508 kB SReclaimable: 1784 kB SUnreclaim: 7724 kB KernelStack: 288 kB PageTables: 184 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 13760 kB Committed_AS: 3572 kB VmallocTotal: 1048372 kB VmallocUsed: 0 kB VmallocChunk: 0 kB root@OpenWrt:/# free total used free shared buffers cached Mem: 27520 25940 1580 124 2112 7268 -/+ buffers/cache: 16560 10960 Swap: 0 0 0 Regards
On 01/06/18 12:34, Lucian Cristian wrote: > On 30.05.2018 20:22, Martin Tippmann wrote: >> find /usr | >> xargs md5sum > > I made the test on tl-wr841n-v9 with luci selected > > these are the changes to squashfs > > --- a/config/Config-images.in > +++ b/config/Config-images.in > @@ -149,8 +149,15 @@ menu "Target Images" > int "Block size (in KiB)" > depends on TARGET_ROOTFS_SQUASHFS > default 64 if LOW_MEMORY_FOOTPRINT > + default 1024 if (SMALL_FLASH && > !LOW_MEMORY_FOOTPRINT) > default 256 > > + config SQUASHFS_FRAGMENT_CACHE_SIZE > + int "Number of fragments cached" > + depends on TARGET_ROOTFS_SQUASHFS > + default 1 if (SMALL_FLASH && > !LOW_MEMORY_FOOTPRINT) > + default 3 > + > menuconfig TARGET_ROOTFS_UBIFS > bool "ubifs" > default y if USES_UBIFS This won't have actually changed the option - you should use KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE, and CONFIG_SQUASHFS_EMBEDDED=y is also needed in the kernel config. I think this also therefore belongs either in Config-kernel.in or simply in the subtarget kernel config. I did a few tests myself: 256K and 3 fragments: 10608K used after boot, 11408K free after reading /usr 24.5 seconds from kernel start to wifi link up 1024K and 3 fragments: 14520K after boot, 15204K after reading 30 seconds to link up 1024K and 2 fragments: 13460K after boot, 14128K after reading 34.7 seconds to link up 1024K and 1 fragment: 11620K after boot, 12364K after reading 46.8 seconds to link up Certainly quite a lot of memory impact with the larger block size, but also a quite significant performance impact with the larger reads. I'm leaning towards compromising on 2 fragments but I'd like input on that.
On Fri, Jun 1, 2018 at 8:05 PM, Alex Maclean <monkeh@monkeh.net> wrote: > On 01/06/18 12:34, Lucian Cristian wrote: > >> On 30.05.2018 20:22, Martin Tippmann wrote: >>> find /usr | >>> xargs md5sum >> >> I made the test on tl-wr841n-v9 with luci selected >> >> these are the changes to squashfs >> >> --- a/config/Config-images.in >> +++ b/config/Config-images.in >> @@ -149,8 +149,15 @@ menu "Target Images" >> int "Block size (in KiB)" >> depends on TARGET_ROOTFS_SQUASHFS >> default 64 if LOW_MEMORY_FOOTPRINT >> + default 1024 if (SMALL_FLASH && >> !LOW_MEMORY_FOOTPRINT) >> default 256 >> >> + config SQUASHFS_FRAGMENT_CACHE_SIZE >> + int "Number of fragments cached" >> + depends on TARGET_ROOTFS_SQUASHFS >> + default 1 if (SMALL_FLASH && >> !LOW_MEMORY_FOOTPRINT) >> + default 3 >> + >> menuconfig TARGET_ROOTFS_UBIFS >> bool "ubifs" >> default y if USES_UBIFS > > This won't have actually changed the option - you should use > KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE, > and CONFIG_SQUASHFS_EMBEDDED=y is also needed in the kernel config. > I think this also therefore belongs either in Config-kernel.in or simply > in the subtarget kernel config. > > I did a few tests myself: > > 256K and 3 fragments: > 10608K used after boot, 11408K free after reading /usr > 24.5 seconds from kernel start to wifi link up > > 1024K and 3 fragments: > 14520K after boot, 15204K after reading > 30 seconds to link up > > 1024K and 2 fragments: > 13460K after boot, 14128K after reading > 34.7 seconds to link up > > 1024K and 1 fragment: > 11620K after boot, 12364K after reading > 46.8 seconds to link up > > Certainly quite a lot of memory impact with the larger block size, but > also a quite significant performance impact with the larger reads. > > I'm leaning towards compromising on 2 fragments but I'd like input on that. Thanks for testing! Did not expect the impact on boot-time. I'm not a dev, 2 looks reasonable for me - maybe add the flag to make menuconfig / .config so that downstream can set it up - for some applications (i.e. freifunk) boot-time does not matter but memory is always scarse. regards Martin
diff --git a/config/Config-images.in b/config/Config-images.in index 90e873edb8..07ef619e70 100644 --- a/config/Config-images.in +++ b/config/Config-images.in @@ -149,6 +149,7 @@ menu "Target Images" int "Block size (in KiB)" depends on TARGET_ROOTFS_SQUASHFS default 64 if LOW_MEMORY_FOOTPRINT + default 1024 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT) default 256 menuconfig TARGET_ROOTFS_UBIFS diff --git a/config/Config-kernel.in b/config/Config-kernel.in index 0cbe5e8351..8eb954e1a5 100644 --- a/config/Config-kernel.in +++ b/config/Config-kernel.in @@ -31,7 +31,7 @@ config KERNEL_CRASHLOG config KERNEL_SWAP bool "Support for paging of anonymous memory (swap)" - default y + default y if !SMALL_FLASH config KERNEL_DEBUG_FS bool "Compile the kernel with debug filesystem enabled" @@ -112,7 +112,7 @@ config KERNEL_DEBUG_KERNEL config KERNEL_DEBUG_INFO bool "Compile the kernel with debug information" - default y + default y if !SMALL_FLASH select KERNEL_DEBUG_KERNEL help This will compile your kernel and modules with debug information. @@ -205,7 +205,7 @@ config KERNEL_COREDUMP config KERNEL_ELF_CORE bool "Enable process core dump support" select KERNEL_COREDUMP - default y + default y if !SMALL_FLASH config KERNEL_PROVE_LOCKING bool "Enable kernel lock checking"
Extend the small_flash feature to disable swap, core dumps, and kernel debug info, and change the squashfs block size to 1024KiB. This saves approximately 18K in the kernel image on ath79, and 64K in the rootfs. Signed-off-by: Alex Maclean <monkeh@monkeh.net> --- config/Config-images.in | 1 + config/Config-kernel.in | 6 +++--- 2 files changed, 4 insertions(+), 3 deletions(-)