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--- linux_wiki:kernel_tuning [2015/04/28 20:11]
billdozor
+++ linux_wiki:kernel_tuning [2019/05/25 23:50]
@@ Line 1: / Line 1: @@
-====== Kernel Tuning ======
-**General Information**
-Kernel tuning using sysctl.conf
-**Checklist**
-  * Any distro, but many examples are done via Red Hat based systems
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-===== Hugepages =====
-Problem: Unable to access a VM's console, and it shows out of memory errors on boot.
-Solution: Reduce the value of "vm.nr_hugepages" to less than 1/2 of total memory in MBs.
-/etc/sysctl.conf
-<code bash>
-vm.nr_hugepages = 1024
-</code>
-hugepage = 2 MBs, so the above is equal to 2GB
-Explanation: Hugepages that is configured to be greater than or equal to total installed memory causes memory starvation during boot due to no memory available for normal use.
-Alternative config location: Hugepages could also be configured at /boot/grub/grub.conf
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-===== Swappiness =====
-TODO: VM Swappiness content will go here.
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-===== File Descriptors =====
-Viewing and setting the system wide file descriptors.
-**View system wide file descriptor information**
-<code bash>
-sysctl fs.file-nr
-fs.file-nr = 6144	0	809542
-</code>
-The three numbers returned:
-  * 6144 = used file descriptors
-  * 0 = allocated but not used
-  * 809542 = system max
-**Change System FD Limits**
-Edit /etc/sysctl.conf
-<code bash>
-fs.file-max = 810542
-</code>
-Example above increases system wide max by 1,000.
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