Questions tagged [performance-tuning]

Performance tuning is the process of modifying a system to improve its efficiency. This is also known as optimizing.

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Postgresql performance seems capped, cannot work out why

I'm setting up a new PG13 cluster, on ubuntu 20.04, virtual machine. The performance I'm seeing, via pgbench, is neither good nor bad. What I'm trying to work out is why it is what it is, and not ...
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Samba and luks encrypted disk together: Huge performance loss despite plenty of CPU resources, LUKS and samba alone works as expected

Setup: SSD encrypted with luks aes-xts 512 bits (256 bits AES key), ext4 filesystem dd write performance of 138 MB/s, CPU usage 97-100 % dd if=/dev/zero of=testfile status=progress bs=32M count=128 ...
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Reducing idle CPU usage of Windows Server 2019 Datacenter Core VM

I'm moving a few installations to Windows Server Datacenter Core 2019 running in KVM VMs on Linux hosts. My first Windows VM has, when it's idle, a bit more than 32000 VM exits per second, half of ...
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Why do most ulimit recommendations call for setting file descriptor limits to 65535?

In searching for max file descriptor ulimit tuning recommendations, many sites recommend setting a file descriptor size of 65535. In some cases, its 100000, 120000, and even higher. Some of these ...
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How To Change /Lib Directory

Production server / is only 50GB and it's full. 23GB is in /lib | /snapd 11GB /flatpak 7GB I see the snap store is installing snaps to /var/lib/snapd | I have a second drive /dev/sdb that has 500GB of ...
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How To Increase Postifx Output Volume

All, I have a new Postfix server that we use to send subscription emails out to customers and send around 200k emails a day. The server is working well, but the queue gets backed up fairly quickly ...
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1answer
30 views

Does MaxClients determine the number of active users in a site

Keeping all factors constant , assuming my apache server is configured as below , in event mpm <IfModule mpm_prefork_module> StartServers 2 MinSpareServers 2 MaxSpareServers 5 MaxClients 200 # ...
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155 views

Apache2 can't handle 200 concurrent requests with 8GB Ram and 4 core cpu

I am load testing a worpress site with loader.io , i am sending 100 concurrent requests per second, running the test in exactly 1 minute. The test fails considerably after 20 seconds or so, nothing ...
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181 views

Clamd performance issues in docker image

We observed performance issues using clamd docker image (https://hub.docker.com/r/mkodockx/docker-clamav/dockerfile) for virus scanning. Our application and clamd (side car deployment) resides on the ...
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Very slow read/write on software raid1 with nvme device on Ubuntu focal

I have a server with Ubuntu 20.04.1 LTS with NVME ssd devices running on raid1 and the hard drive operates so slow! to open a gzip file to of 500MB to a 3.7GB takes a while.. way more then it should. ...
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How to find out the mySQL query which uses most of the CPU using performance_sc

52893 TID is using 100% CPU in my server How to find the query corresponds to that TID? For me, this table is empty
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How to do performance tuning of Apache server?

We have an apache server 2.4.X which we are using as a reverse proxy in front of one Java Application . We have enabled Apache status module Apache Status and we are able to see that number of idle ...
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Shingled magnetic recording(SMR) device managed - sequential write performance optimizations

recently (2020-05) many HDD producers were caught silently replacing CMR lines with SMR disks, which brought more exposure to the whole concept. It seems that most device-managed SMR disks first ...
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85 views

CPU C-states disabling ruins network performance

With intel_idle.max_cstate=1: root@debian:~# curl -o /dev/null http://xx.xx.38.35:999/speedtest/1000mb % Total % Received % Xferd Average Speed Time Time Time Current ...
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What can be a reason for different clock speeds between sockets on 2 x Xeon Scalable 6148?

I have server with dual Xeon Scalable 6148 CPUs running HPC application. Base clock: 2.4GHz All core Turbo: 3.1 GHz Some processing threads are not scaling well and are sensitive to cpu clock. I ...
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How to improve performance of Nginx for high PHP processing load?

I wonder how I could improve the performance of my server? It is configured with Ubuntu 18.04 (LTS), 4 GB RAM, 100 GB SSD, 2 CPU, with Nginx 1.14.0 and PHP 7.2-fpm to handle running and serving a site ...
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220 views

How to determine HugePages count?

I have a number of servers that we use as KVM hypervisor nodes. We want to enable hugepages and leverage this features for performance related matters. I have looked online on how to enable hugepages,...
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product import is broke behind cloudflare

Im having trouble to resolve my database errors and how to optimize it. Coz of the slowness of my server (mostly querries i believe), my imports turns with a cloudflare error code. (Cloudflare blocks ...
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87 views

Index rollover latency

I have created an ILM policy as follows, { "policy": { "phases": { "hot": { "min_age": "0ms", "actions": { "rollover": { "max_docs": 30 }, ...
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Any ideas on tuning single stream tcp performance?

I'm a newbie to TCP tuning and would really like some pointers to possible solutions. I have a Ubuntu 18.04 server with maximum bandwidth of 30Mbps. But simple downloading like scp or wget can only ...
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1answer
708 views

Is there is any tool/way to find out why packet is getting dropped due to an arp cache full?

My developer hypothesis is packet is getting dropped at arp layer. We increased the default value of neigh.default.gc_thresh3 1024 --> 2048 and now everything looks good. But I want to understand is ...
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1answer
337 views

Bottleneck identification using iostat, vmstat, mpstat

I am doing some Apache and MySQL performance tests, then upgrading a single component and running tests again to see where the bottlenecks are. I have a local used server warehouse (Tams in Lindon UT) ...
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1answer
180 views

Does F5 HTTP/2 profile need tuning?

The current default for the F5 HTTP/2 profile has a Concurrent Streams Per Connection default of 10. This seems a bit conservative. IETF recommended that this value being no smaller than 100, so as to ...
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Maria Performance Tuning: HyperThreading is great for marketing, lousy for performance [closed]

I'm looking into optimizing my database server and this is what I read in Maria's official documentation here. How true is this? More so, how is this true? Apologies if this is not the best place ...
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DoS attack? Vast majority of apache workers in 'Reading Request' mode, site down last night, slow now

So I think my server might be suffering a Denial of Service attack. We got notified by pingdom (website monitoring) that our website was unavailable starting around 3AM. Early today we started ...
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407 views

Apache performance tuning for high traffic with MPM Event

I currently manage the following set of servers that serve about 700 web pages: SERVER 1 (WEB) Web server: Apache 2.4.29 with MPM Event PHP 7.2.22 CPU: Intel Xeon CPU E5-2673 v4 @2.30GHz (4 cores) ...
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Possible reasons Distribution of durations is tri-modal

Below is the distribution graph of durations from a single page of an asp.net webforms application. As you can see there is a cluster of response times in the 250ms range, there is a cluster in the ...
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476 views

MySQL LOAD DATA INFILE: Better Server, Worse Performance

I am testing out Microsoft Azure Database for MySQL and have run into a performance issue that I do not understand. I launched a "Basic" server with 1 vCore (2 GB RAM, "Standard Storage"), which is ...
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1answer
518 views

Packet drop on HP ProLiant DL360 G9 running RHEL 6.10

We have a HP ProLiant DL360 G9 running RHEL 6.10 with 2 X Intel 82599ES 10-Gigabit SFI/SFP+. HP product name is HP Ethernet 10Gb 2-port 560SFP+ Adapter eth5 and eth6 showing a lot of packet drop (...
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2answers
1k views

Serving a static website with nginx. Response time over 600 milliseconds. What’s wrong?

I serve a wordpress blog with nginx http cached to over 99% of the requests with a cache lifetime of 2 days. Here’s a webpage from the site. The webpages have quite a few images and therefore lazy ...
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1answer
2k views

how to reach 1M concurrent TCP connections?

I am trying to setup a environment with multiple nodes (1 receiver + 16 senders) to establish 1,000,000 (1M) concurrent TCP connections. Using this tool: https://github.com/Microsoft/ntttcp-for-linux ...
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Soak test failing on AWS RDS MySQL

I have a MySQL database in AWS RDS. It is an r4.large machine with 16GB ram. I have been testing its load capacity and find out that upto 18 concurrent users, the app works fine. Then we decided to do ...
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2answers
261 views

Apache Tuning for 512GB RAM

Use Case: API Server Cluster Optimized for JSON Data Submission I have a distributed application sending info to API servers that are slaves of a MySQL 8 master. Applications do full initial sync (~...
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1answer
250 views

Online performance tuning apache tomcat

I'm relatively new to this field and not sure whether I'm posting the question in the correct forum. I'm trying to do online parameter tuning for the TPC-W benchmark. (It is a 3-tier web application ...
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2answers
113 views

How to ask antivirus software to work slower and hence use less disk access?

It is our policy for our end-user's computers (usually laptops) to have high power CPUs, GPUs, RAMs (no less than 16GB) and HDD space (1TB), but we save money by choosing lower rotation speed of HDD. ...
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5answers
2k views

Options for performance improvements on very big Filesystems and high IOWAIT

I have a Ubuntu 16.04 Backup Server with 8x10TB HDD via a SATA 3.0 Backplane. The 8 Harddisks are assembled to a RAID6, an EXT4 Filesystem is in use. This Filesystem stores a huge amount of small ...
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2answers
92 views

Is it possible for Windows clients to carry out external queries through an alternative DNS server directly?

Our Windows domain is far away. DNS performance is affected. Would it be possible for Windows clients to carry out external queries through an alternative DNS server directly? I understand this is not ...
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1answer
570 views

Debugging and fine-tuning the linux process scheduler

When debugging sporadic web application slowdowns, I've found that all the processes have quite high maximum scheduling delay. # perf sched record -- sleep 10 && perf sched latency --sort max ...
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1answer
1k views

Nginx: Optimizing server response time for a HTTP cached website

I have a website with all of the pages served from nginx’s http cache and rarely invalidated or expired. The average total page download size is around 2 MB But despite being a static site with no ...
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1answer
117 views

Nginx performance issues with single user reqesting but with large configuration file

I have following configuration used in server block and as the number of locations grew, the performance has degraded substantially even if there is only one request (e.g. https://example.com/loc1/...
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2answers
300 views

what is the IOPS behavior when partitions of single disk are used in an LVM?

I have an ubuntu 14.04.1 LTS server which have LVM(backed by hardware RAID5) with logical volume and a volume group named "dbstore-lv" and "dbstore-vg" which have sdb1 sdb2 sdb3 created from same sdb ...
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1answer
2k views

php memory_limit vs kubernetes resource memory limit

I'm new to Kubernetes and I'm trying to figure out what resource limits I should set for my php webapp. My first guess is that if I have configured php fpm to use a maximum of 256M of memory then ...
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101 views

Performance on Pinned CPU cores versus automatically managed?

I have a XenServer 7.5 environment where I'm running a single Windows VM with 16 total vCPU's. My server has dual Xeon E5-2620v4 CPU's with 8cores/16threads each clocked at 2.1GHz nominal and a Max ...
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1answer
74 views

How do I tune a single-threaded server to be amazingly fast? [closed]

We have a license manager server that runs on a single host. It accepts TCP connections, performs some sort of exchange (I haven’t reverse-engineered it), and keeps the TCP connection open for the ...
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1answer
2k views

Recommended Apache tuning configuration [duplicate]

My web server has configuration 16 GB RAM 8vCPU (Hexcore). Apache version 2.4. There will be massive site visit. So what will be the best and recommended Apache tuning configuration ? I am using ...
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1answer
817 views

Slow apache response time for json api (solved)

I've got an Apache server hosting several json APIs. This server is running Ubuntu 16.04.4 LTS with Apache and Mysql. Response times for all API are very good except for one! It takes about 5s to ...
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2answers
455 views

Dual-port RDMA Throughput Issue

I have two nodes connected with dual-port Mellanox Connext-X3 VPI HCAs via an IB switch. The nodes are two socket machines with Hasswell CPUs and 2 16GB DIMMs per each socket (totaling 64GB). ...
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1answer
2k views

Apache handshaking slow on prefork configuration, need config tuning

My server, running Ubuntu 14/Apache2.4.7, has an htaccess redirect to force all requests to use HTTPS. Generally, it responds quickly. However, I recently altered my SSL config to restrict the ciphers ...
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2answers
614 views

DRBD weird speed dips

couple of weeks ago I made a test setup for DRBD on couple of servers. The speed was fixed 90MB/800Mb as per my config for initial sync. Now I have reinstalled the OS (CentOS 7.4) to do final install ...
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1answer
488 views

Misunderstanding about Page Cache and dirty_background_bytes

I've been looking at this for a while now and things aren't lining up with my expectations, but I don't know if it's because something is off, or if my expectations are wrong. So, I've got a system ...

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