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| author | Conrad Meyer <cem@FreeBSD.org> | 2019-08-19 00:02:19 -0700 |
|---|---|---|
| committer | Pedro Alves <palves@redhat.com> | 2019-08-20 15:06:37 +0100 |
| commit | aedbe3bb9f03be12ad714adca1fefc391317bd94 (patch) | |
| tree | 577892888ccb5462341d72bc9056f6c46edbe16f /gdb | |
| parent | ac533243beac35f158341d53edab53031218bcde (diff) | |
| download | gdb-aedbe3bb9f03be12ad714adca1fefc391317bd94.zip gdb-aedbe3bb9f03be12ad714adca1fefc391317bd94.tar.gz gdb-aedbe3bb9f03be12ad714adca1fefc391317bd94.tar.bz2 | |
Improve remote attach round-trips without btrace
For remotes which do not support btrace at all, we can save several
round trips for each thread. This is especially significant when your
remote is a kernel with 100s or 1000s of threads and latency is
intercontinental.
Previously, with target, remote, and infrun debugging enabled, one
might see:
Sending packet: $Hg18aee#43...Ack
Packet received: OK
Sending packet: $Hg186f7#eb...Ack
Packet received: OK
remote:target_xfer_partial (24, , 0x805454000, 0x0, 0x0, 4096) = -1, 0
repeated for all non-exited threads.
Afterwards, if the remote does not specify 'qXfer:btrace-conf:read+'
in qSupported stub features, these unnecessary thread switches are
avoided.
gdb/ChangeLog:
* remote.c (remote_target::remote_btrace_maybe_reopen): Avoid
unnecessary thread walk if remote doesn't support the packet.
Diffstat (limited to 'gdb')
| -rw-r--r-- | gdb/ChangeLog | 5 | ||||
| -rw-r--r-- | gdb/remote.c | 5 |
2 files changed, 10 insertions, 0 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 2dce609..d9e676a 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2019-08-20 Conrad Meyer <cem@FreeBSD.org> + + * remote.c (remote_target::remote_btrace_maybe_reopen): Avoid + unnecessary thread walk if remote doesn't support the packet. + 2019-08-19 Tom Tromey <tromey@adacore.com> * python/py-value.c (value_has_field): Fix indentation. diff --git a/gdb/remote.c b/gdb/remote.c index 7ea9cd4..ae06c4b 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -13700,6 +13700,11 @@ remote_target::remote_btrace_maybe_reopen () int warned = 0; #endif + /* Don't bother walking the entirety of the remote thread list when + we know the feature isn't supported by the remote. */ + if (packet_support (PACKET_qXfer_btrace_conf) != PACKET_ENABLE) + return; + scoped_restore_current_thread restore_thread; for (thread_info *tp : all_non_exited_threads ()) |