Does Yocto Linux load manage the cores on a multiple core CPU? Tried looking for info on forums, etc. Can't find a definite answer. Thanks!

$ file /lib/ld-linux.so.2 /lib/ld-linux.so.2: symbolic link to i386-linux-gnu/ld-2.27.so $ readlink -f /lib/ld-linux.so.2 /lib/i386-linux-gnu/ld-2.27.so $ file /lib/i386-linux-gnu/ld-2.27.so /lib/i386-linux-gnu/ld-2.27.so: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), dynamically linked, BuildID[sha1]=7a59ed1836f27b66ffd391d656da6435055f02f8, stripped So is ld-2.27.so a shared library? It is said to be a dynamic linker/loader and mentioned in section 8 of man . So is it an executable? If yes, why is it named like a shared library as *.so? If no, how shall I understand it is like an executable, for being a dynamic linker/loader and mentioned in section 8 of man? Thanks.

My website is being DoS'ed by Google webspiders. Google is welcome to index my site, but sometimes it is querying a tagcloud on my site faster than my webserver can produce the results, making my webserver run out of resources. How can I limit access to my webserver in such a way that normal visitors are not affected? robots.txt is no option because it would block the whole site from being indexed. iptables -m recent is tricky, because some pages have a lot of images or other data files and 'recent' triggers on those too (typically my RSS aggregator, loading images and feeds). iptables -m limit has the same disadvantage and on top of that, I wasn't able to be selective per IP source address. How can I limit visitors that cause my server load to rise too high? I am running apache2 on Ubuntu server in a VirtualBox VM.

I recently received a MacBook Pro with an M1 pro CPU, which has 2 "efficiency" cores and 8 performance cores. When I run htop/btop/top I get a load average of >2 because the process scheduler always assigns certain lower-demand processes to the efficiency cores, which results in those cores always running at 60 to 100% capacity. I feel like the 2 efficiency cores reduce the utility of the load average metric, which was already reduced due to multiple cores. Back in the dim, distant past we had single core CPUs that the load average made intuitive sense on. However now we have 2 types of CPU core in a single system, and my most recent phone has 3 different types of core: efficiency, performance, and a single ultra performance core. How should such a new load average be calculated? Are there any ongoing efforts to redefine a general system-load metric? Since efficiency cores are made to run low priority processes, perhaps excluding those from the default metric makes sense? Then divide the remaining load value among the non-efficiency CPUs. For instance, a load average of 3.4. Subtract 2 for the efficiency cores, 1.4. Then divide by the number of performance cores, 1.4 / 8 = 0.175.

We have set up LVM stripping across 06 disk in our DB server for improving IOPS performance. However during heavy load, it has been observed that device-mapper **dm-2** asscociated with these 6 disks is having 100% utlization (busy), but the associated disks **sd[c-h]** have only ~50% utilization. Bcoz of the heavy load and 100% utilization, DB server, hence app performance also degrades. Here is the screenshot of busy percentage: Here is LV details:

--- Logical volume ---
  LV Path                /dev/vg/lg
  LV Name                lv
  VG Name                vg
  LV UUID                P**-***-***e
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2022-12-02 20:32:38 +0000
  LV Status              available
  # open                 1
  LV Size                13.08 TiB
  Current LE             13715376
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     8192
  Block device           253:2
   
  --- Segments ---
  Logical extents 0 to 13715375:
    Type		striped
    Stripes		6
    Stripe size	16.00 KiB

Below is the block size of the underlying file system:

$ sudo stat -f /lvm-fs
  File: "/home/.../lvm-fs"
    ID: ***    Namelen: 255     Type: xfs
Block size: 4096       Fundamental block size: 4096
Blocks: Total: 3510614400 Free: 2161893661 Available: 2161893661
Inodes: Total: 1404454400 Free: 1404453939

Is there any configuration/settings such that **dm-0** and other disks should experience equal utilization % so that IOPS performance can improve further ? Thanks. **Edit-1:** Output of linear read using **dd** :

$ sudo dd if=/dev/dm-2 of=/dev/null bs=1M count=102400 
102400+0 records in
102400+0 records out
107374182400 bytes (107 GB) copied, 184.611 s, 582 MB/s

For above **dd** command, busy % kept fluctuating between 65% and 85%, but never touched 100% whereas **dm-2** was always 100% busy as below:

I've been trying to determine the source of high load on a system, **top:** top - 09:55:12 up 1 day, 11:48, 4 users, load average: 7.64, 6.52, 6.33 Tasks: 279 total, 2 running, 276 sleeping, 0 stopped, 1 zombie %Cpu(s): 50.0 us, 50.0 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st MiB Mem : 1785.3 total, 223.3 free, 938.8 used, 623.2 buff/cache MiB Swap: 4096.0 total, 2259.5 free, 1836.5 used. 664.8 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1267200 root 20 0 0.1g 0.0g 0.0g R 50.0 0.3 0:00.61 top 1 root 20 0 0.2g 0.0g 0.0g S 0.0 0.3 347:46.38 /usr/lib/systemd/systemd --switched-root --system --deserialize 17 2 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.15 [kthreadd] 3 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [rcu_gp] 4 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [rcu_par_gp] 6 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [kworker/0:0H-events_highpri] 9 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [mm_percpu_wq] 10 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [rcu_tasks_rude_] 11 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [rcu_tasks_trace] 12 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 6:10.89 [ksoftirqd/0] 13 root 20 0 0.0g 0.0g 0.0g I 0.0 0.0 0:41.25 [rcu_sched] 14 root rt 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [migration/0] 15 root rt 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.12 [watchdog/0] 16 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [cpuhp/0] 18 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [kdevtmpfs] 19 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [netns] 20 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:03.12 [kauditd] 21 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.11 [khungtaskd] 22 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [oom_reaper] 23 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.01 [writeback] 24 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 0:01.01 [kcompactd0] 25 root 25 5 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [ksmd] 26 root 39 19 0.0g 0.0g 0.0g S 0.0 0.0 0:07.19 [khugepaged] 27 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [crypto] 28 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [kintegrityd] 29 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [kblockd] 30 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [blkcg_punt_bio] 31 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [tpm_dev_wq] 32 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [md] 33 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [edac-poller] 34 root rt 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [watchdogd] 35 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:10.06 [kworker/0:1H-kblockd] 69 root 20 0 0.0g 0.0g 0.0g S 0.0 0.0 5:12.96 [kswapd0] 171 root 0 -20 0.0g 0.0g 0.0g I 0.0 0.0 0:00.00 [kthrotld] 172 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/24-pciehp] 173 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/25-pciehp] 174 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/26-pciehp] 175 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/27-pciehp] 176 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/28-pciehp] 177 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/29-pciehp] 178 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/30-pciehp] 179 root -51 0 0.0g 0.0g 0.0g S 0.0 0.0 0:00.00 [irq/31-pciehp] **vmstat:** procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free inact active si so bi bo in cs us sy id wa st 6 0 1676376 66624 929468 403424 109 160 1073 274 120 95 13 18 69 0 0 **iostat:** Linux 4.18.0-425.13.1.el8_7.x86_64 (hostname) 04/20/2023 _x86_64_ (1 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 12.30 0.82 17.65 0.26 0.00 68.97 Device tps kB_read/s kB_wrtn/s kB_read kB_wrtn sda 38.05 1064.79 272.12 138382106 35365399 dm-0 10.39 250.39 25.20 32540656 3274422 dm-1 66.44 107.65 158.12 13989760 20548928 dm-2 2.39 147.00 11.90 19103775 1546792 dm-3 0.00 0.03 0.02 3989 2082 dm-4 3.45 152.32 31.33 19795688 4071283 dm-5 0.30 2.01 5.01 260581 651253 dm-6 0.00 0.03 0.02 3440 2048 dm-7 0.02 0.06 0.18 8149 23581 dm-8 0.06 0.80 0.27 104186 34788 dm-9 0.30 9.03 0.11 1173075 14455 dm-10 8.83 387.11 39.96 50309334 5192814 loop0 0.00 0.01 0.00 1917 101 loop1 0.00 0.03 0.00 3332 1 How can I debug the cause of this further?

I want to do performance test on Oracle Linux 8 KVM guest server (It will be used as Application server (WLS 14c) and/or Oracle DB server). What are the best tools I can provide this with? I saw an RPM called stress. Does it help in completing necessary tests for network, CPU, memory and I/O? Or how can I do them all individually in the most consistent way? What are the most successful RPMs or system commands? (dd for example I/O) Note: the servers are not used instantly, I want to create a virtual (contrived) load. Thanks in advance and best regards.

Load Average itself is not very informative about the reasons of overload, so I want an additional characteristic: the percent of disk read operations that are done from cache. To measure it, I probably need: - the amount of data read from cache (or, instead, the amount of data read directly from disk); - the total amount of read data. Both for the certain period of time, f.e., 1 second. Is this information available in procfs/sysfs?

uptime piped to sed fixes the first part but what about memory usage? top runs, at least by default, interactively. So: I need to watch used RAM excluding opportunistic caching(which gets dropped as soon as the memory is needed). And ask about both because I expect a single standard tool can do it, instead of two. Or - even better - something in /proc indicating the RAM part.

I am launching non interactive jobs using batch, and I would like to increase the load limiting factor in order to use all 8 of my cores. I am on Ubuntu 16.04 LTS. From what I understand, batch uses atd to do the jobs. Jobs start when the load factor goes under a threshold, called the *load limiting factor*. It is said in the man of atd that we can change this factor using the -l option. My question: how can I use this atd -l XX option? When I type, for instance, atd -l 7.2 before batch, it doesn't seem to be changing anything. What I have found so far: - In this question https://unix.stackexchange.com/questions/292555/how-to-run-bash-script-via-multithreading/292598#292598 , one contributor proposes to do this in the 'atd service starting script'. I guess that it refers to the /etc/init.d/atd, but I do not know what to change there, cf next bullet point. - I have found pages, such as this one http://searchitchannel.techtarget.com/feature/Understanding-run-level-scripts-in-Fedora-11-and-RHEL , where they propose to: "modify the following line (in the start section) of the /etc/init.d/atd script: daemon /usr/sbin/atd. Replace it with this line, using the -l argument to specify the new minimum system load value: daemon /usr/sbin/atd -l 1.6". However, there is no such a line in /etc/init.d/atd. It seems that it can be introduced in the /etc/init.d/atd, but I do not know where. I have never changed such files. So, how can I change the load limiting factor used by the batch command?

I noticed that GRUB gets stuck and tries to load attached external usb hard drive instead of the internal HDD. If I remove external HDD during boot then it loads immediately. Is there a way I can stop GRUB to look at attached external HDD, atleast until it's loaded linux completely. Attached external HDD has media files & is not bootable but it has few tera bytes of data. I use the machine as plex server & need the external HDD attached if system is rebooted. In the GRUB logs I see it gets stuck at this point - Using makefile-style concurrent boot in runlevel S. Starting hotplugevents dispatcher: systemd-udevd. Synthesizing the initial hotplus events (subsystems)... done. Synthesizing the initial hotplug events (devices)...done. Waiting for /dev to be fully populated...done. Any suggestions? Linux version Is MX-21_x64, kernel 5.10.0-11

I'm working on performance testing of application and would like to validate the performance of the server during testing. Currently, the server is a 16 multiprocessor with single core on each CPU. I'm validating the CPU utilization of the server using the top command and I'm getting the load average value as 0.47,0.37,0.22. I'm trying to understand the load average of the server however, getting confused. Does the value show for single CPU or for 16 CPUs available? Kindly help with answers. Also please help with other commands to validate the performance of server.

Just now I was forced to remotely reboot my CentOS 6.3 system due to a ultra high load (75!) that paralyzed the system. This is a web/mail server that serves a wordpress blog (mySQL + PHP). Is there any log I can analyze and try to discover what cause that? This is the email I have received now from the system about the event yesterday: This is an automated message notifying you that the 5 minute load average on your system is 75.91. This has exceeded the 10 threshold. One Minute - 83.24 Five Minutes - 75.91 Fifteen Minutes - 39.35 top - 22:25:30 up 122 days, 7:28, 0 users, load average: 99.14, 80.70, 42.31 Tasks: 298 total, 1 running, 297 sleeping, 0 stopped, 0 zombie Cpu(s): 1.2%us, 0.5%sy, 0.0%ni, 98.1%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1020176k total, 956828k used, 63348k free, 2788k buffers Swap: 4194296k total, 1391900k used, 2802396k free, 25164k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 20 0 19352 448 444 S 0.0 0.0 0:08.27 /sbin/init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kthreadd] 3 root RT 0 0 0 0 S 0.0 0.0 0:09.43 [migration/0] 4 root 20 0 0 0 0 S 0.0 0.0 1884:48 [ksoftirqd/0] 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/0] 6 root RT 0 0 0 0 S 0.0 0.0 0:06.06 [watchdog/0] 7 root RT 0 0 0 0 S 0.0 0.0 0:07.81 [migration/1] 8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/1] 9 root 20 0 0 0 0 S 0.0 0.0 7:25.62 [ksoftirqd/1] 10 root RT 0 0 0 0 S 0.0 0.0 0:04.58 [watchdog/1] 11 root 20 0 0 0 0 S 0.0 0.0 4:48.95 [events/0] 12 root 20 0 0 0 0 S 0.0 0.0 9:13.85 [events/1] 13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [cgroup] 14 root 20 0 0 0 0 S 0.0 0.0 0:08.21 [khelper] 15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [netns] 16 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [async/mgr] 17 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [pm] 18 root 20 0 0 0 0 S 0.0 0.0 0:21.72 [sync_supers] 19 root 20 0 0 0 0 S 0.0 0.0 0:20.65 [bdi-default] 20 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kintegrityd/0] 21 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kintegrityd/1] 22 root 20 0 0 0 0 S 0.0 0.0 5:26.09 [kblockd/0] 23 root 20 0 0 0 0 S 0.0 0.0 0:22.90 [kblockd/1] I am not sure if this can help. Everything appears to be using 0% of CPU.. this is another email.. This is an automated message notifying you that the 5 minute load average on your system is 70.53. This has exceeded the 10 threshold. One Minute - 94.79 Five Minutes - 70.53 Fifteen Minutes - 32.68 top - 22:23:34 up 122 days, 7:26, 0 users, load average: 96.88, 74.74, 35.91 Tasks: 283 total, 2 running, 281 sleeping, 0 stopped, 0 zombie Cpu(s): 1.2%us, 0.5%sy, 0.0%ni, 98.1%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1020176k total, 970440k used, 49736k free, 3196k buffers Swap: 4194296k total, 1249404k used, 2944892k free, 29836k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 6715 apache 20 0 217m 7804 3252 D 1.9 0.8 0:00.28 /usr/sbin/httpd -k start -DSSL 6770 apache 20 0 218m 8772 3368 D 1.9 0.9 0:00.28 /usr/sbin/httpd -k start -DSSL 6799 apache 20 0 301m 8088 3184 D 1.9 0.8 0:00.14 /usr/sbin/httpd -k start -DSSL 7265 root 20 0 15160 1220 808 R 1.9 0.1 0:00.02 /usr/bin/top -c -b -n 1 7266 root 20 0 15160 1220 808 R 1.9 0.1 0:00.02 /usr/bin/top -c -b -n 1 1 root 20 0 19352 448 444 S 0.0 0.0 0:08.27 /sbin/init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [kthreadd] 3 root RT 0 0 0 0 S 0.0 0.0 0:09.43 [migration/0] 4 root 20 0 0 0 0 S 0.0 0.0 1884:48 [ksoftirqd/0] 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/0] 6 root RT 0 0 0 0 S 0.0 0.0 0:06.06 [watchdog/0] 7 root RT 0 0 0 0 S 0.0 0.0 0:07.81 [migration/1] 8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 [migration/1] 9 root 20 0 0 0 0 S 0.0 0.0 7:22.58 [ksoftirqd/1] 10 root RT 0 0 0 0 S 0.0 0.0 0:04.58 [watchdog/1] 11 root 20 0 0 0 0 S 0.0 0.0 4:48.95 [events/0] 12 root 20 0 0 0 0 S 0.0 0.0 9:13.85 [events/1] 13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [cgroup] 14 root 20 0 0 0 0 S 0.0 0.0 0:08.21 [khelper] 15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [netns] 16 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [async/mgr] 17 root 20 0 0 0 0 S 0.0 0.0 0:00.00 [pm] 18 root 20 0 0 0 0 S 0.0 0.0 0:21.72 [sync_supers] Yes, I am using Apache. 75 is the load average saw on top for the last 5 minutes.

I'm getting the following output from top: Cpu(s): 43.8%us, 32.5%sy, 4.8%ni, 2.0%id, 15.6%wa, 0.2%hi, 1.2%si, 0.0%st Mem: 16331504k total, 15759412k used, 572092k free, 4575980k buffers Swap: 4194296k total, 260644k used, 3933652k free, 1588044k cached the output from iostat -xk 6 shows the following: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 360.20 86.20 153.40 1133.60 2054.40 26.61 1.51 6.27 0.77 18.38 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdd 22.60 198.80 17.40 31.60 265.60 921.60 48.46 0.18 3.70 1.67 8.20 sdc 16.80 218.20 22.20 23.40 261.60 966.40 53.86 0.21 4.56 1.49 6.78 Based on the above it looks like something must be overloaded. But what? ### Questions 1. If its not the harddisk or the CPU then what? 2. It seems as though 15.6% of the CPU's time is spent waiting. What exactly could it be waiting for?

After I rescue some disk, I copy the result (disk image of several TBs ) from local network data storage (LNDS) to target disk as a file. Usualy the filesystem of the target disk is NTFS. The LNDS is capable to pass data to me at the speed > 600MB/s (on 10Gbit network). The target disk is capable to save data at sustain speed >150 MB/s. But the speed of copying file from the server to target disk filesystem is damned slower, etwa 60-80MB/s. Today I was asked to prepare two copy. Well, I used the tee command to specify two targets: dd if=/servermount/path/file.img bs=8192 |tee /localmount/target1/file.img >/localmount/target2/file.img (cp cannot be forked with tee) But what surprized me: the copy speed is about 40MB/s only. I immediately started to analyse the trafic: The network is loading data at the sustained speed of 40MB/s, and both disks writes at max speed 160MB/s but less then 25% of the time. I have looked the top and found that the CPU spends most time with two mount.ntfs processes - each takes >40% - and tee which takes about 30% of CPU time. I tried also a revers process: I started a samba server on my workstation, added the two targets as share, and sended the data from server to the two disks. I was surprised again, because the common speed has grown to 66 - 69 MB/s and the mount.ntfs processes were spending just about 7% CPU time. I cannot understand, why there was such great difference between push and pull over the net, and other way than it could be expected. Not all bash command are suitable for piping with tee. The dd if targeted to /dev/null gives the speed of 650-700MB/s. If I copy the physical disk to two other phys. disks (no metter if making clones or creating two disk images) the copy speed is over 120MB/s, and the same I get if the target is on the server (LNDS). Can some body explain me, what I did wrong. Is there some copy command more suitable for copying large file from LNDS to two local disks?

I have this question that I need an answer to. What makes programs like st , zathura , sxiv , and feh load instantly and what makes programs like VS Code and Google Chrome load so slowly in low-spec computers? For example, I have a low-spec laptop running Linux Mint. And when I execute **st**, it instantly opens an **st** instance, but when I execute **Google Chrome**, it takes a long time to open a **Google Chrome** instance. What makes st load faster than Google Chrome and what makes Google Chrome load slower than st. Thank you! :)

man ksoftirqd indicates that: > If ksoftirqd is taking more than a tiny percentage of CPU time, this > indicates the machine is under heavy soft interrupt load. I'm working with a Debian Wheezy system under generally high system utilization in which ksoftirqd processes utilizes excessive cpu and disk resources for a short period of time. During that time, the system operates at a snails pace. How can one begin to understand what the root cause is for this ksoftirqd resource utilization spikes?

In Linux, what are the executable ELF files respectively for - static linker - dynamic linker - loader - dynamic loader? Which of them are invoked - by execve() - by dlopen()? How are they invoked by execve() or dlopen(), to solve the chicken-egg problem that execve() or dlopen() are used for invoking executable files? Thanks.

I'm using an AWS remote Linux machine for for Load testing. Presently I'm using "top" command Then I also piped few more commands in it to get java specific services For RAM usage I'm using "free" command. Now I wanted to calculate average CPU and RAM % while I run the application, lets say for 10-15 testing flow, how may I calculate that?

on our servers, typing sar show's the system load statistics for today starting at midnight, is it possible to show yesterdays statistics?