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Dear Alex,
**What kind of hit ratio do you get with rock if you do not limit swap-rate
and do not specify swap-timeout? [i also removed the max size as recomended], the gain ratio is max 13 %.
**What
kind of hit ratio do you get with rock if you use one worker, one
rock cache_dir, do not limit swap-rate, do not specify swap-timeout, and start Squid with -N to disable SMP? [ as recomended, only one rock cache_dir , no limit swap and excuted with -N option,the gain ration is 7%] additonial info:
i have a total of 24 GB RAM which i use 15 GB of them as cache_mem and i use ext4 in fstab.
thank u
From: Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx>
Sent: Saturday, July 4, 2020 3:40 AM To: patrick mkhael <patrick.mkhael@xxxxxxxxxxx>; squid-users@xxxxxxxxxxxxxxxxxxxxx <squid-users@xxxxxxxxxxxxxxxxxxxxx> Subject: Re: [squid-users] rock issue On 7/3/20 4:50 AM, patrick mkhael wrote:
> workers 3 > cpu_affinity_map process_numbers=1,2,3,4,5,6 cores=1,2,3,4,5,6 > cache_dir rock /rock1 200000 max-size=32000 swap-timeout=300 max-swap-rate=100 > cache_dir rock /rock2 200000 max-size=32000 max-swap-rate=100 swap-timeout=300 > cache_dir rock /rock3 200000 max-size=32000 max-swap-rate=100 swap-timeout=300 > cache_mem 17 GB > maximum_object_size_in_memory 25 MB > maximum_object_size 1 GB > cache_miss_revalidate off > quick_abort_pct 95 FYI: The combination of 1GB maximum_object_size and much smaller size limits for objects in memory and disk caches does not make sense: There is no cache to store a, say, 26MB object. If Squid lacks the corresponding configuration "lint" check, somebody should add it. > This config is giving 4% of cache gain ratio, > in addition as i already mentionned before if i take the same above > config without worker and cach_dir with the same traffiic using aufs on > one of the disks , i have automatically i har 60 % cache ratio. When using AUFS, do you limit disk-cached object sizes to 32KB like you do with rock? If not, then you should remove the max-size limit from rock cache_dirs. Modern rock cache_dirs are capable of storing large objects. What kind of hit ratio do you get with rock if you do not limit swap-rate and do not specify swap-timeout? What kind of hit ratio do you get with rock if you use one worker, one rock cache_dir, do not limit swap-rate, do not specify swap-timeout, and start Squid with -N to disable SMP? As you can see, I am trying to understand whether the size limitation, the rate limiting, or SMP problems explain the drop in hit ratio. > Shoud rock give me the same performance as aufs ? It is a difficult question to answer correctly (for me). The goal is for rock performance to exceed that of (a)ufs, but I doubt we have reached that goal in every environment that matters (including yours). * In a non-SMP environment, I would expect similar hit ratios in most cases, but I would not be surprised if there are significant exceptions. Rock is focused on SMP support, and there are complexities/costs associated with SMP. Rock is getting better, but there are some known areas where rock cannot yet do what ufs (including aufs) can. * In a SMP environment, the question is mostly meaningless because there is no SMP support for ufs-based caches. Folks use squid.conf preprocessor hacks to configure ufs-based caches in SMP mode, but those setups usually violate HTTP and may cause serious problems. YMMV. > for a traffic of 1 Gb/s , is there a way to use aufs ? Before trying unsupported combinations of aufs and SMP, I would try to understand why your hit ratio is so low with rock. The questions above may be a good start in that investigation. Cheers, Alex. > ------------------------------------------------------------------------ > *From:* Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx> > *Sent:* Thursday, July 2, 2020 4:24 PM > *To:* patrick mkhael <patrick.mkhael@xxxxxxxxxxx>; > squid-users@xxxxxxxxxxxxxxxxxxxxx <squid-users@xxxxxxxxxxxxxxxxxxxxx> > *Subject:* Re: [squid-users] rock issue > > On 7/1/20 4:45 PM, patrick mkhael wrote: > >> ***Please note that you have 20 kids worth mapping (10 workers and 10 >> diskers), but you map only the first 10.{since i did not get the point >> of the diskers ,as far as i understood , it should be like (simple >> example) > >>> workers 2 >>> cpu_affinity_map process_numbers=1,2,3,4 cores=1,2,3,4 >>> cache_dir rock ... >>> cache_dir rock ... > > The above looks OK. Each worker is a kid process. Each rock cache_dir is > a kid process (we call them diskers). If you have physical CPU cores to > spare, give each kid process its own physical core. Otherwise, give each > worker process its own physical core (if you can). Diskers can share > physical cores with less harm because they usually do not consume much > CPU cycles. Squid wiki has more detailed information about that: > https://wiki.squid-cache.org/Features/SmpScale#How_to_configure_SMP_Squid_for_top_performance.3F > > >> ***Why do you have 10 rock caches of various sizes? [ to be honest , i >> saw in many websites that it should be like this from the smallest to >> the bigest with diff size, i tought it should serve from small size pool >> to high ] > > IMHO, you should stop reading those web pages :-). There is no general > need to segregate objects by sizes, especially when you are using the > same slot size for all cache_dirs. Such segregation may be necessary in > some special cases, but we have not yet established that your case is > special. > > >> *****How many independent disk spindles (or equivalent) do you have? [ i >> have one raid 5 ssd disks , used by the 10 rock cache dir] > > Do not use RAID. If possible, use one rock cache_dir per SSD disk. The > only reason this may not be possible, AFAICT, is if you want to cache > more (per SSD disk) than a single Squid cache_dir can hold, but I would > not worry about overcoming that limit at the beginning. If you want to > know more about the limit, look for "33554431" in > http://www.squid-cache.org/mail-archive/squid-users/201312/0034.html > > >> ***How did you select the swap rate limits and timeouts for >> cache_dirs?[I took it also from online forum , can i leave it empty for >> both] > > If you want a simple answer, then it is "yes". Unfortunately, there is > no simple correct answer to that question. To understand what is going > on and how to tune things, I recommend studying the Performance Tuning > section of https://wiki.squid-cache.org/Features/RockStore > > >> ****Do you see any ERRORs or WARNINGs in cache log?[NO error or warning >> found in cache] > > Good. I assume you do see some regular messages in cache.log. Keep an > eye for ERRORs and WARNINGs as you change settings. > > > HTH, > > Alex. |
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