Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760670Ab0G3TS2 (ORCPT ); Fri, 30 Jul 2010 15:18:28 -0400 Received: from mail.windriver.com ([147.11.1.11]:33857 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760626Ab0G3TSE (ORCPT ); Fri, 30 Jul 2010 15:18:04 -0400 From: Jason Wessel To: linux-kernel@vger.kernel.org Cc: kgdb-bugreport@lists.sourceforge.net, mingo@elte.hu, Jason Wessel Subject: [PATCH 02/15] gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol Date: Fri, 30 Jul 2010 14:17:23 -0500 Message-Id: <1280517456-1167-3-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.4.rc1 In-Reply-To: <1280517456-1167-1-git-send-email-jason.wessel@windriver.com> References: <1280517456-1167-1-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 30 Jul 2010 19:17:41.0017 (UTC) FILETIME=[E12B9090:01CB301B] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3741 Lines: 121 The gdb debugger understands how to parse short versions of the thread reference string as long as the bytes are paired in sets of two characters. The kgdb implementation was always sending 8 leading zeros which could be omitted, and further optimized in the case of non-negative thread numbers. The negative numbers are used to reference a specific cpu in the case of kgdb. An example of the previous i386 stop packet looks like: T05thread:00000000000003bb; New stop packet response: T05thread:03bb; The previous ThreadInfo response looks like: m00000000fffffffe,0000000000000001,0000000000000002,0000000000000003,0000000000000004,0000000000000005,0000000000000006,0000000000000007,000000000000000c,0000000000000088,000000000000008a,000000000000008b,000000000000008c,000000000000008d,000000000000008e,00000000000000d4,00000000000000d5,00000000000000dd New ThreadInfo response: mfffffffe,01,02,03,04,05,06,07,0c,88,8a,8b,8c,8d,8e,d4,d5,dd A few bytes saved means better response time when using kgdb over a serial line. Signed-off-by: Jason Wessel --- kernel/debug/gdbstub.c | 37 +++++++++++++++++++------------------ 1 files changed, 19 insertions(+), 18 deletions(-) diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c index 3517fd7..e117cfd 100644 --- a/kernel/debug/gdbstub.c +++ b/kernel/debug/gdbstub.c @@ -367,28 +367,31 @@ static void error_packet(char *pkt, int error) * remapped to negative TIDs. */ -#define BUF_THREAD_ID_SIZE 16 +#define BUF_THREAD_ID_SIZE 8 static char *pack_threadid(char *pkt, unsigned char *id) { - char *limit; + unsigned char *limit; + int lzero = 1; + + limit = id + (BUF_THREAD_ID_SIZE / 2); + while (id < limit) { + if (!lzero || *id != 0) { + pkt = pack_hex_byte(pkt, *id); + lzero = 0; + } + id++; + } - limit = pkt + BUF_THREAD_ID_SIZE; - while (pkt < limit) - pkt = pack_hex_byte(pkt, *id++); + if (lzero) + pkt = pack_hex_byte(pkt, 0); return pkt; } static void int_to_threadref(unsigned char *id, int value) { - unsigned char *scan; - int i = 4; - - scan = (unsigned char *)id; - while (i--) - *scan++ = 0; - put_unaligned_be32(value, scan); + put_unaligned_be32(value, id); } static struct task_struct *getthread(struct pt_regs *regs, int tid) @@ -601,7 +604,7 @@ static void gdb_cmd_query(struct kgdb_state *ks) { struct task_struct *g; struct task_struct *p; - unsigned char thref[8]; + unsigned char thref[BUF_THREAD_ID_SIZE]; char *ptr; int i; int cpu; @@ -621,8 +624,7 @@ static void gdb_cmd_query(struct kgdb_state *ks) for_each_online_cpu(cpu) { ks->thr_query = 0; int_to_threadref(thref, -cpu - 2); - pack_threadid(ptr, thref); - ptr += BUF_THREAD_ID_SIZE; + ptr = pack_threadid(ptr, thref); *(ptr++) = ','; i++; } @@ -631,8 +633,7 @@ static void gdb_cmd_query(struct kgdb_state *ks) do_each_thread(g, p) { if (i >= ks->thr_query && !finished) { int_to_threadref(thref, p->pid); - pack_threadid(ptr, thref); - ptr += BUF_THREAD_ID_SIZE; + ptr = pack_threadid(ptr, thref); *(ptr++) = ','; ks->thr_query++; if (ks->thr_query % KGDB_MAX_THREAD_QUERY == 0) @@ -851,7 +852,7 @@ int gdb_serial_stub(struct kgdb_state *ks) memset(remcom_out_buffer, 0, sizeof(remcom_out_buffer)); if (kgdb_connected) { - unsigned char thref[8]; + unsigned char thref[BUF_THREAD_ID_SIZE]; char *ptr; /* Reply to host that an exception has occurred */ -- 1.6.4.rc1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/