On 2/15/26 8:00 PM, Alex Rousskov wrote:
On 2026-02-14 14:45, Brad House wrote:
I've got a squid deployment where serving from cache can be slower
than an uncached download. I'm seeing speeds of around 50MB/s when
serving from cache, which is much slower than anticipated. Infact,
when hitting fast upstream servers, serving of a non-cached asset is
faster (even though its still hitting squid to fetch it).
I'm thinking there's got to be something wrong with my squid
configuration, I'm currently running on Rocky Linux 10 with Squid
6.10-6.
The VM I'm using currently has 4 cores, 16G RAM and 100G of usable
space. I used fio to measure disk performance and I got
* Random Write: 3629MiB/s (1MB block), 33.2k (4k block) IOPS
* Random Read: 8391MiB/s (1MB block), 43.5k (4k block) IOPS
What speed to you get when Squid serves the object from the memory
cache? Do not configure a disk cache for this test to make sure that
Squid is not reading from disk...
I cannot help with AUFS cache_dirs, but _if_ AUFS code uses 4KByte I/O
blocks, then 50MByte/s you are measuring is equivalent to 12K IOPS
which is arguably not that bad for that long-neglected AUFS code
(compared to "raw" 44K IOPS performance you measured with fio)!
Please note that I am not trying to imply that rock cache_dir with a
large slot-size setting would work faster than AUFS. And even if
properly configured rock does work faster than AUFS, I would be really
surprised if Squid can approach Traffic Server performance! The two
projects had vastly different focus and resources.
HTH,
Alex.
I'll need to wait until the weekend to give the memory-only cache a
try. Do you have any suggested Rock settings I should try while I'm
testing things? I'm ok wasting disk space on smaller items if it means
it can serve from cache faster in general.
Thanks.
-Brad
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