Remove extra spaces around a function argument.

Use bitmask to indicate which protocol versions to try.
Also remove duplicate check.

I make multiple read-only connection for installworld/installkernel from different machines.
Otherwise, I use ggate to export some ufs file systems.
I could use nfs for these as well.

Address some of problems pointed by code review.

The slowness issue existed back in a decade ago around 6.1-RELEASE and some years/releases thereafter.

Thank you for checking this again.
It was also my bad that the problem wasn't described well enough.

Stop using PR* formatter.
Tested on i386 and amd64.

ggate defines its offset in unsigned int 64 as below.
So, printing negative numbers from printf indicates using a wrong formatter.

Thank you for your support, Mark.
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=132845 is the corresponding bugzilla entry.

Verify paths are the same between handshakes for a single session.

Moved close() to connection_remove() and aligned with send/recv fds.

First of all, thank you for your quick response.

Added static to implementatoin; follow style of other existing static functions.

Drop unnecessary NULL check. This is a field on a struct and won't be NULL.

I think I addressed all of feed backs so far.
I'm wondering if someone can take a look.

Address other review comments.

Fixed style, moved 0 assignment to *before and *after when SWWAPBLK_NONE,
and adjusted if/else statement for *after case.

Split backward and forward search into separate functions for ease of reading.

Thank you for quick response, Mark.

Updated function name in comment.

Changed its prefix to swdevt.

Check NULL pointers explicitly.

Restore KASSERT.

Update and merge D22437.

It looks we better drop swp_pager_meta_ctl() changes from this, D22324, and let D22409 take over the lookup implementation while dropping SWM_POP for simpler diff.
D22409 change is to optimize swap_pager_haspage() with additional searches after successful pindex lookup.

Dropped self-test.

D22280 has been committed.

Correct swblk index and exclude swp_pager_swblk_free_empty() changes.

I don't think this code duplication in swap_pager_copy() is a good idea.
I updated D22256 to avoid the double lookup cost from the first revision.
I'm still testing the 2nd version though.

Fixed spaces/style.

Created swp_pager_meta_find_least private API to find and delete in a single
operation. swap_pager_find_least calls it for look up.

Suspend for now.

I've been using the comparison based optimization for 2 weeks on current
following daily, buildworld/buildkernel daily and haven't seen an issue
with this approach.

I see. I just added zfs/zvol swap space temporary from command line within the last a couple of weeks for other reasons. I see few of too early OOM on few of machines although it is very rare and spontaneous such that it hasn't been easy to find a trigger.

swap_pager_full != 0 was indeed too aggressive. I'm wondering if we can feed in swap space usage such that we can delay OOM electing at low usage and push for OOM at high usage.

That's another idea.
I will check the code and test if that is also an option.

Thanks for follow up, markj.

Use "== SWPG_LOW" comparison for almost full warning.
Drop swp_gauge > SWPG_LOW comparison for high watermark check.

The only reason I created a patch was to proceed removal of sys/dir.h in the base system.
Given the upstream source hasn't been updated for more than a couple of decade.
It looks the code still assume 20 year old standard.

But sysctl describes totally different:

Skipping is about https://svnweb.freebsd.org/base/head/sys/vm/swap_pager.c?revision=352407&view=markup#l2313

destLen -> destlen.

Thanks.

Remove uninteded debug print.

Also print length with PRIu32.

Include zutil.h instead of zlib.h in order to pick up OS_CODE and DEF_MEM_LEVEL.